Add tests for duplicated operationId (#20070)

* add tests for duplicated operation id

* add spec file

modules/openapi-generator/src/test/resources/3_0/duplicated_operationid.yaml

@@ -0,0 +1,58 @@
+openapi: 3.0.0
+servers:
+  - url: 'http://petstore.swagger.io/v2'
+info:
+  description: A sample spec to test duplicated operationId
+  version: 1.0.0
+  title: OpenAPI Petstore
+  license:
+    name: Apache-2.0
+    url: 'https://www.apache.org/licenses/LICENSE-2.0.html'
+paths:
+  '/pet/{petId}':
+    get:
+      tags:
+        - pet
+      summary: Find pet by ID
+      description: Returns a single pet
+      operationId: getObject
+      parameters:
+        - name: petId
+          in: path
+          description: ID of pet to return
+          required: true
+          schema:
+            type: integer
+            format: int64
+      responses:
+        '200':
+          description: successful operation
+        '400':
+          description: Invalid ID supplied
+        '404':
+          description: Pet not found
+  '/user/{username}':
+    get:
+      tags:
+        - user
+      summary: Get user by user name
+      description: ''
+      operationId: getObject
+      parameters:
+        - name: username
+          in: path
+          description: The name that needs to be fetched. Use user1 for testing.
+          required: true
+          schema:
+            type: string
+      responses:
+        '200':
+          description: successful operation
+        '400':
+          description: Invalid username supplied
+        '404':
+          description: User not found
+externalDocs:
+  description: Find out more about Swagger
+  url: 'http://swagger.io'
+