Handle custom content type example

modules/openapi-generator/src/main/java/org/openapitools/codegen/examples/ExampleGenerator.java

@@ -170,6 +170,9 @@ public List<Map<String, String>> generate(Map<String, Object> examples, List<Str
                         kv.put(EXAMPLE, example);
                         output.add(kv);
                     }
+                } else {
+                    kv.put(EXAMPLE, null);
+                    output.add(kv);
                 }
             }
         } else {

modules/openapi-generator/src/test/java/org/openapitools/codegen/java/spring/SpringCodegenTest.java

@@ -1404,6 +1404,30 @@ public void testPutItemsMethodContainsKeyInSuperClassMethodCall_issue12494() thr
             .bodyContainsLines("super.putSomeMapItem(key, someMapItem);");
     }
 
+    @Test
+    public void shouldHandleCustomResponseType_issue11731() throws IOException {
+        File output = Files.createTempDirectory("test").toFile().getCanonicalFile();
+        output.deleteOnExit();
+
+        OpenAPI openAPI = new OpenAPIParser()
+            .readLocation("src/test/resources/bugs/issue_11731.yaml", null, new ParseOptions()).getOpenAPI();
+        SpringCodegen codegen = new SpringCodegen();
+        codegen.setLibrary(SPRING_BOOT);
+        codegen.setOutputDir(output.getAbsolutePath());
+
+        ClientOptInput input = new ClientOptInput()
+            .openAPI(openAPI)
+            .config(codegen);
+
+        DefaultGenerator generator = new DefaultGenerator();
+        Map<String, File> files = generator.opts(input).generate().stream()
+            .collect(Collectors.toMap(File::getName, Function.identity()));
+
+        JavaFileAssert.assertThat(files.get("CustomersApi.java"))
+            .assertMethod("getAllUsingGET1")
+            .bodyContainsLines("if (mediaType.isCompatibleWith(MediaType.valueOf(\"application/hal+json\"))) {");
+    }
+
     @Test
     public void shouldHandleContentTypeWithSecondWildcardSubtype_issue12457() throws IOException {
         File output = Files.createTempDirectory("test").toFile().getCanonicalFile();

modules/openapi-generator/src/test/resources/bugs/issue_11731.yaml

@@ -0,0 +1,59 @@
+openapi: 3.0.2
+info:
+  title: Petstore - OpenAPI 3.0
+  description: Specification to reproduce issues with mediatypes other than common application/json
+  termsOfService: http://inss.ch
+  contact:
+    email: openapi@inss.ch
+  license:
+    name: Apache 2.0
+    url: http://www.apache.org/licenses/LICENSE-2.0.html
+  version: 1.0.0
+servers:
+- url: http://localhost:8080/api/v3
+
+paths:
+  /customers:
+    get:
+      tags:
+      - customer-controller
+      summary: getAll
+      operationId: getAllUsingGET_1
+      responses:
+        200:
+          description: OK
+          content:
+            application/hal+json:
+              schema:
+                $ref: '#/components/schemas/ResponseObject'
+        401:
+          description: Unauthorized
+          content: {}
+        403:
+          description: Forbidden
+          content: {}
+        404:
+          description: Not Found
+          content: {}
+
+components:
+  schemas:
+    ResponseObject:
+      required:
+      - name
+      - photoUrls
+      type: object
+      properties:
+        id:
+          type: integer
+          format: int64
+          example: 10
+          description: 'Id'
+        status:
+          type: string
+          description: pet status in the store
+          enum:
+          - available
+          - pending
+          - sold
+          example: available