#602 Generated code does not implement model inheritance correctly

src/main/java/io/swagger/codegen/v3/generators/java/SpringCodegen.java

@@ -15,6 +15,7 @@
 import io.swagger.codegen.v3.SupportingFile;
 import io.swagger.codegen.v3.generators.features.BeanValidationFeatures;
 import io.swagger.codegen.v3.generators.features.OptionalFeatures;
+import io.swagger.codegen.v3.generators.util.OpenAPIUtil;
 import io.swagger.codegen.v3.utils.URLPathUtil;
 import io.swagger.v3.oas.models.OpenAPI;
 import io.swagger.v3.oas.models.Operation;
@@ -27,11 +28,7 @@
 import java.io.IOException;
 import java.io.Writer;
 import java.net.URL;
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
+import java.util.*;
 import java.util.regex.Matcher;
 import java.util.stream.Collectors;
 
@@ -792,6 +789,60 @@ public void postProcessModelProperty(CodegenModel model, CodegenProperty propert
         }
     }
 
+    @Override
+    public Map<String, Object> postProcessAllModels(Map<String, Object> objs) {
+        Map<String, Object> allProcessedModels = super.postProcessAllModels(objs);
+
+        List<Object> allModels = new ArrayList<Object>();
+        for (String name: allProcessedModels.keySet()) {
+            Map<String, Object> models = (Map<String, Object>)allProcessedModels.get(name);
+            try {
+                allModels.add(((List<Object>) models.get("models")).get(0));
+            } catch (Exception e){
+                e.printStackTrace();
+            }
+        }
+
+        additionalProperties.put("parent", modelInheritanceSupport(allModels));
+
+        return allProcessedModels;
+    }
+
+    protected List<Map<String, Object>> modelInheritanceSupport(List<?> allModels) {
+        Map<CodegenModel, List<CodegenModel>> byParent = new LinkedHashMap<>();
+        for (Object model : allModels) {
+            Map entry = (Map) model;
+            CodegenModel parent = ((CodegenModel)entry.get("model")).parentModel;
+            if(null!= parent) {
+                byParent.computeIfAbsent(parent, k -> new LinkedList<>()).add((CodegenModel)entry.get("model"));
+            }
+        }
+
+        List<Map<String, Object>> parentsList = new ArrayList<>();
+        for (Map.Entry<CodegenModel, List<CodegenModel>> parentModelEntry : byParent.entrySet()) {
+            CodegenModel parentModel = parentModelEntry.getKey();
+            List<Map<String, Object>> childrenList = new ArrayList<>();
+            Map<String, Object> parent = new HashMap<>();
+            parent.put("classname", parentModel.classname);
+            List<CodegenModel> childrenModels = byParent.get(parentModel);
+            for (CodegenModel model : childrenModels) {
+                Map<String, Object> child = new HashMap<>();
+                child.put("name", model.name);
+                child.put("classname", model.classname);
+                childrenList.add(child);
+            }
+            parent.put("children", childrenList);
+            parent.put("discriminator", parentModel.discriminator);
+            if(parentModel.discriminator != null && parentModel.discriminator.getMapping() != null)
+            {
+                parentModel.discriminator.getMapping().replaceAll((key, value) -> OpenAPIUtil.getSimpleRef(value));
+            }
+            parentsList.add(parent);
+        }
+
+        return parentsList;
+    }
+
     @Override
     public Map<String, Object> postProcessModelsEnum(Map<String, Object> objs) {
         objs = super.postProcessModelsEnum(objs);

src/main/resources/handlebars/JavaSpring/model.mustache

@@ -1,6 +1,6 @@
 package {{package}};
 
-{{^x-is-composed-model}}
+{{^isComposedModel}}
 import java.util.Objects;
 {{#imports}}import {{import}};
 {{/imports}}
@@ -21,20 +21,20 @@ import com.fasterxml.jackson.dataformat.xml.annotation.JacksonXmlProperty;
 {{#withXml}}
 import javax.xml.bind.annotation.*;
 {{/withXml}}
-{{/x-is-composed-model}}
+{{/isComposedModel}}
 
 {{#models}}
 {{#model}}
-{{#vendorExtensions.x-is-composed-model}}
+{{#isComposedModel}}
 {{>interface}}
-{{/vendorExtensions.x-is-composed-model}}
-{{^vendorExtensions.x-is-composed-model}}
+{{/isComposedModel}}
+{{^isComposedModel}}
 {{#isEnum}}
 {{>enumOuterClass}}
 {{/isEnum}}
 {{^isEnum}}
 {{>pojo}}
 {{/isEnum}}
-{{/vendorExtensions.x-is-composed-model}}
+{{/isComposedModel}}
 {{/model}}
 {{/models}}

src/main/resources/handlebars/JavaSpring/typeInfoAnnotation.mustache

@@ -1,7 +1,14 @@
 {{#jackson}}
 @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "{{discriminator.propertyName}}", visible = true )
 @JsonSubTypes({
-  {{#children}}
-  @JsonSubTypes.Type(value = {{classname}}.class, name = "{{^vendorExtensions.x-discriminator-value}}{{name}}{{/vendorExtensions.x-discriminator-value}}{{#vendorExtensions.x-discriminator-value}}{{{vendorExtensions.x-discriminator-value}}}{{/vendorExtensions.x-discriminator-value}}"),
-  {{/children}}
-}){{/jackson}}
+  {{#if discriminator.mapping}}
+    {{#each discriminator.mapping}}
+        @JsonSubTypes.Type(value = {{this}}.class, name = "{{@key}}"),
+    {{/each}}
+  {{else}}
+    {{#children}}
+        @JsonSubTypes.Type(value = {{classname}}.class, name = "{{name}}"),
+    {{/children}}
+  {{/if}}
+})
+{{/jackson}}