use map/array model class only if it is generated (#17612)

* fix

* tests

* generate samples

* refactor

samples/client/petstore/java/feign/api/openapi.yaml

@@ -1029,6 +1029,25 @@ paths:
       - fake
       x-content-type: application/json
       x-accepts: application/json
+  /fake/stringMap-reference:
+    post:
+      description: ""
+      operationId: testStringMapReference
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/MapOfString'
+        description: request body
+        required: true
+      responses:
+        "200":
+          description: successful operation
+      summary: test referenced string map
+      tags:
+      - fake
+      x-content-type: application/json
+      x-accepts: application/json
   /fake/inline-additionalProperties:
     post:
       description: ""
@@ -1874,6 +1893,11 @@ components:
       additionalProperties: true
       description: A schema consisting only of additional properties
       type: object
+    MapOfString:
+      additionalProperties:
+        type: string
+      description: A schema consisting only of additional properties of type string
+      type: object
     OuterEnum:
       enum:
       - placed

samples/client/petstore/java/feign/src/main/java/org/openapitools/client/api/FakeApi.java

@@ -1042,4 +1042,31 @@ public interface FakeApi extends ApiClient.Api {
       return this;
     }
   }
+
+  /**
+   * test referenced string map
+   * 
+   * @param requestBody request body (required)
+   */
+  @RequestLine("POST /fake/stringMap-reference")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  void testStringMapReference(Map<String, String> requestBody);
+
+  /**
+   * test referenced string map
+   * Similar to <code>testStringMapReference</code> but it also returns the http response headers .
+   * 
+   * @param requestBody request body (required)
+   */
+  @RequestLine("POST /fake/stringMap-reference")
+  @Headers({
+    "Content-Type: application/json",
+    "Accept: application/json",
+  })
+  ApiResponse<Void> testStringMapReferenceWithHttpInfo(Map<String, String> requestBody);
+
+
 }