diff --git a/modules/openapi-generator/src/main/resources/typescript-axios/apiInner.mustache b/modules/openapi-generator/src/main/resources/typescript-axios/apiInner.mustache
index 167ac8408493..9f798331db7c 100644
--- a/modules/openapi-generator/src/main/resources/typescript-axios/apiInner.mustache
+++ b/modules/openapi-generator/src/main/resources/typescript-axios/apiInner.mustache
@@ -189,7 +189,8 @@ export const {{classname}}AxiosParamCreator = function (configuration?: Configur
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
     {{#hasFormParams}}
             localVarRequestOptions.data = localVarFormParams{{#vendorExtensions}}{{^multipartFormData}}.toString(){{/multipartFormData}}{{/vendorExtensions}};
     {{/hasFormParams}}
diff --git a/samples/client/petstore/typescript-axios/builds/default/api.ts b/samples/client/petstore/typescript-axios/builds/default/api.ts
index 3592be77d5fb..afe31b598e69 100644
--- a/samples/client/petstore/typescript-axios/builds/default/api.ts
+++ b/samples/client/petstore/typescript-axios/builds/default/api.ts
@@ -290,7 +290,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -341,7 +342,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -388,7 +390,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -435,7 +438,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -478,7 +482,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -523,7 +528,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -582,7 +588,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -640,7 +647,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
@@ -1016,7 +1024,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1053,7 +1062,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1088,7 +1098,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1124,7 +1135,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1340,7 +1352,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1378,7 +1391,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1416,7 +1430,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1453,7 +1468,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1488,7 +1504,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1535,7 +1552,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1564,7 +1582,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1606,7 +1625,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/es6-target/api.ts b/samples/client/petstore/typescript-axios/builds/es6-target/api.ts
index 3592be77d5fb..afe31b598e69 100644
--- a/samples/client/petstore/typescript-axios/builds/es6-target/api.ts
+++ b/samples/client/petstore/typescript-axios/builds/es6-target/api.ts
@@ -290,7 +290,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -341,7 +342,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -388,7 +390,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -435,7 +438,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -478,7 +482,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -523,7 +528,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -582,7 +588,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -640,7 +647,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
@@ -1016,7 +1024,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1053,7 +1062,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1088,7 +1098,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1124,7 +1135,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1340,7 +1352,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1378,7 +1391,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1416,7 +1430,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1453,7 +1468,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1488,7 +1504,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1535,7 +1552,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1564,7 +1582,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1606,7 +1625,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/with-complex-headers/api.ts b/samples/client/petstore/typescript-axios/builds/with-complex-headers/api.ts
index 66c69d869462..bed5634db46d 100644
--- a/samples/client/petstore/typescript-axios/builds/with-complex-headers/api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-complex-headers/api.ts
@@ -339,7 +339,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof pet !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(pet !== undefined ? pet : {}) : (pet || "");
 
@@ -390,7 +391,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -437,7 +439,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -484,7 +487,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -527,7 +531,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -572,7 +577,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof pet !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(pet !== undefined ? pet : {}) : (pet || "");
 
@@ -631,7 +637,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -689,7 +696,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
@@ -1071,7 +1079,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1108,7 +1117,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1143,7 +1153,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1179,7 +1190,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof order !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(order !== undefined ? order : {}) : (order || "");
 
@@ -1395,7 +1407,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof user !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(user !== undefined ? user : {}) : (user || "");
 
@@ -1433,7 +1446,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof user !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(user !== undefined ? user : {}) : (user || "");
 
@@ -1471,7 +1485,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof user !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(user !== undefined ? user : {}) : (user || "");
 
@@ -1508,7 +1523,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1543,7 +1559,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1590,7 +1607,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1619,7 +1637,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1661,7 +1680,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof user !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(user !== undefined ? user : {}) : (user || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/with-interfaces/api.ts b/samples/client/petstore/typescript-axios/builds/with-interfaces/api.ts
index efbe9589e12d..f9a81f26f0d7 100644
--- a/samples/client/petstore/typescript-axios/builds/with-interfaces/api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-interfaces/api.ts
@@ -290,7 +290,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -341,7 +342,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -388,7 +390,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -435,7 +438,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -478,7 +482,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -523,7 +528,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -582,7 +588,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -640,7 +647,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
@@ -1109,7 +1117,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1146,7 +1155,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1181,7 +1191,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1217,7 +1228,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1480,7 +1492,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1518,7 +1531,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1556,7 +1570,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1593,7 +1608,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1628,7 +1644,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1675,7 +1692,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1704,7 +1722,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1746,7 +1765,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/pet-api.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/pet-api.ts
index 0d01d428b7ae..37f48bb8801a 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/pet-api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/pet-api.ts
@@ -65,7 +65,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -116,7 +117,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -163,7 +165,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -210,7 +213,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -253,7 +257,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -298,7 +303,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -357,7 +363,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -415,7 +422,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/store-api.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/store-api.ts
index 302b1bcd470c..e3d3a50cdf2b 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/store-api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/store-api.ts
@@ -54,7 +54,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -91,7 +92,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -126,7 +128,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -162,7 +165,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/user-api.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/user-api.ts
index c06bbbcde132..ce60b09973bb 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/user-api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version-and-separate-models-and-api/api/another/level/user-api.ts
@@ -55,7 +55,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -93,7 +94,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -131,7 +133,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -168,7 +171,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -203,7 +207,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -250,7 +255,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -279,7 +285,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -321,7 +328,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
diff --git a/samples/client/petstore/typescript-axios/builds/with-npm-version/api.ts b/samples/client/petstore/typescript-axios/builds/with-npm-version/api.ts
index 3592be77d5fb..afe31b598e69 100644
--- a/samples/client/petstore/typescript-axios/builds/with-npm-version/api.ts
+++ b/samples/client/petstore/typescript-axios/builds/with-npm-version/api.ts
@@ -290,7 +290,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -341,7 +342,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -388,7 +390,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -435,7 +438,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -478,7 +482,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -523,7 +528,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -582,7 +588,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams.toString();
 
             return {
@@ -640,7 +647,8 @@ export const PetApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             localVarRequestOptions.data = localVarFormParams;
 
             return {
@@ -1016,7 +1024,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1053,7 +1062,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1088,7 +1098,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1124,7 +1135,8 @@ export const StoreApiAxiosParamCreator = function (configuration?: Configuration
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1340,7 +1352,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1378,7 +1391,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1416,7 +1430,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");
 
@@ -1453,7 +1468,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1488,7 +1504,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1535,7 +1552,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1564,7 +1582,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
 
             return {
                 url: globalImportUrl.format(localVarUrlObj),
@@ -1606,7 +1625,8 @@ export const UserApiAxiosParamCreator = function (configuration?: Configuration)
             localVarUrlObj.query = {...localVarUrlObj.query, ...localVarQueryParameter, ...options.query};
             // fix override query string Detail: https://stackoverflow.com/a/7517673/1077943
             delete localVarUrlObj.search;
-            localVarRequestOptions.headers = {...localVarHeaderParameter, ...options.headers};
+            let headersFromBaseOptions = baseOptions && baseOptions.headers ? baseOptions.headers : {};
+            localVarRequestOptions.headers = {...localVarHeaderParameter, ...headersFromBaseOptions, ...options.headers};
             const needsSerialization = (typeof body !== "string") || localVarRequestOptions.headers['Content-Type'] === 'application/json';
             localVarRequestOptions.data =  needsSerialization ? JSON.stringify(body !== undefined ? body : {}) : (body || "");