diff --git a/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache b/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
index 50827b3cc40d..cf9883bae6e3 100644
--- a/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
+++ b/modules/openapi-generator/src/main/resources/Java/libraries/jersey3/ApiClient.mustache
@@ -989,7 +989,7 @@ public class ApiClient{{#jsr310}} extends JavaTimeFormatter{{/jsr310}} {
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
         if (param.getValue() instanceof Iterable) {
-          Stream.of(param.getValue).forEach(v -> addParamToMultipart(v, param.getKey, multiPart));
+          Stream.of(param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }
diff --git a/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java b/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
index 8ebd3a1666a0..e91ac76ff231 100644
--- a/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
+++ b/samples/client/petstore/java/jersey3/src/main/java/org/openapitools/client/ApiClient.java
@@ -991,7 +991,7 @@ public Entity<?> serialize(Object obj, Map<String, Object> formParams, String co
       MultiPart multiPart = new MultiPart();
       for (Entry<String, Object> param: formParams.entrySet()) {
         if (param.getValue() instanceof Iterable) {
-          Stream.of(param.getValue).forEach(v -> addParamToMultipart(v, param.getKey, multiPart));
+          Stream.of(param.getValue()).forEach(v -> addParamToMultipart(v, param.getKey(), multiPart));
         } else {
           addParamToMultipart(param.getValue(), param.getKey(), multiPart);
         }