Add validation for response examples to make sure keys are media types defined.

Before filling a bug

• have you checked the faq for known issues.
• have you checked existing issues (probably related to #4244)

Describe the bug

Swagger config

{
  "swagger": "2.0",
  "info": {
    "version": "v2",
    "title": "API",
    "description": ""
  },
  "host": "example.com",
  "basePath": "/rest",
  "schemes": [
    "https",
    "http"
  ],
  "paths": {
    "/api/Actions/{id}": {
      "get": {
        "tags": [
          "Actions"
        ],
        "summary": "Get an action by it's identifier.",
        "operationId": "Actions_GetOne",
        "consumes": [],
        "produces": [
          "application/json",
          "text/json"
        ],
        "parameters": [
          {
            "name": "id",
            "in": "path",
            "description": "The action identifier (UID)",
            "required": true,
            "type": "string",
            "format": "uuid"
          }
        ],
        "responses": {
          "200": {
            "description": "OK"
          },
          "400": {
            "description": "Bad Request",
            "schema": {
              "$ref": "#/definitions/ValidationError"
            },
            "example": {
              "Message": "The provided text was too long. Expected < 150 characters",
              "Key": "text"
            }
          },
          "404": {
            "description": "Not Found",
            "schema": {
              "$ref": "#/definitions/ResponseMessage"
            },
            "example": {
              "Message": "Restr"
            }
          },
          "401": {
            "description": "Unauthorised - a bearer token is required."
          }
        },
        "security": [
          {
            "oauth2": []
          }
        ]
      }
    }
  },
  "definitions": {
    "ResponseMessage": {
      "type": "object",
      "properties": {
        "Message": {
          "type": "string"
        }
      }
    },
    "ValidationError": {
      "type": "object",
      "properties": {
        "Message": {
          "type": "string"
        },
        "Key": {
          "type": "string"
        }
      }
    }
  }
}

Autorest config

input-file: test.json
verbose: true
debug: true
csharp:
  namespace: Example.Client
  output-folder: csharp/Client
  enable-xml: true
  add-credentials: true

Validation via swagger-cli: yarn run swagger-cli validate test.json:

test.json is valid

yarn run autorest Error message:

AutoRest code generation utility [cli version: 3.3.2; node: v12.22.4]
(C) 2018 Microsoft Corporation.
https://aka.ms/autorest
NOTE: AutoRest core version selected from configuration: ~3.1.0.
Network Enabled: true
   Loading AutoRest core      'C:\Users\twsl\.autorest\@autorest_core@3.1.3\node_modules\@autorest\core\dist' (3.1.3)
INFORMATION: > Loading AutoRest extension '@autorest/csharp' (latest->3.0.0-beta.20210803.1)
INFORMATION: > Loading AutoRest extension '@autorest/modelerfour' (4.19.3->4.19.3)

WARNING (PreCheck/CheckDuplicateSchemas): Checking for duplicate schemas, this could take a (long) while.  Run with --verbose for more detail.
C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\modelerfour\dist\main.js - FAILURE  {} Error: Not able to process media type Message at this moment.
    at ModelerFour.filterMediaTypes (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:1369:21)
    at ModelerFour.processResponses (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:2058:36)
    at ModelerFour.processOperation (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:1672:10)
    at ModelerFour.process (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:2327:14)
    at processRequest (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\plugin-modelerfour.ts:23:31)
    at C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\libs\extension-base\dist\extension-base.js:55:1
PLUGIN FAILURE: Not able to process media type Message at this moment., Error: Not able to process media type Message at this moment.
    at ModelerFour.filterMediaTypes (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:1369:21)
    at ModelerFour.processResponses (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:2058:36)
    at ModelerFour.processOperation (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:1672:10)
    at ModelerFour.process (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\modelerfour.ts:2327:14)
    at processRequest (C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\@autorest\src\modeler\plugin-modelerfour.ts:23:31)
    at C:\Users\twsl\.autorest\@autorest_modelerfour@4.19.3\node_modules\libs\extension-base\dist\extension-base.js:55:1, {}
FATAL: Error: Not able to process media type Message at this moment.
C:\Users\twsl\.autorest\@autorest_core@3.1.3\node_modules\@autorest\core\dist\src_lib_autorest-core_ts.js - FAILURE {}
  Error: Plugin modelerfour reported failure.
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

Expected behavior Create a simple API client.

Additional context Autorest version: 3.3.2 Node version: tested with 12.22.4, 14.17.4, 16.6.1 Switching to v3 context via --v3 produces the same results. At some point with an earlier version of the api and autorest i was able to generate a client successfully. Unfortunately I don’t remember the version of autorest used.

[timotheeguerin]

Well yes and no. Client generation don’t make use of it now but autorest is not limited to client generation and some other tools might. Either way the main problem is actually due to the fact that autorest convert swagger 2.0 to openapi 3.0 first and during this conversion if you have invalid examples then it creates new responses with those mime types.

For example on editor.swagger.io if you convert your spec it produces this(About the same is produced by autorest): And this is definitely incorrect.

However it could maybe just be a warning that remove the invalid examples instead of a strict error.

[timotheeguerin]

Yes, the actual specificiation(can’t link the actual section “Example Object”) define the type of examples under response as Dict<mimeType, any> and the content under the mimeType being freeform.

Seems like neither editor.swagger.io nor autorest will do validation on that. Should probably change that to prevent this confusing error later down the pipeline.