[BUG] Code generates unreachable branches

Description

When reviewing client go code generated with this tool, we noticed that for status code responses < 300 the client generates unreachable code paths

openapi-generator version

4.2.2 pulled from maven

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: API
  version: 1.0.0
  description:
    Xx
  contact:
    name: XXX
    url: http://www.xxxs.com/
    email: support@xxx.com

servers:
   - url: http://{url}:{port}/XXX/v1
     variables:
       url:
         default: 'localhost'
       port:
         default: '7999'

tags:
  - name: XXX
    description: Operations 


paths:
  /status:
    get:
      tags:
         - XXX
      summary: Gets the status of the system time service.
      operationId: getStatus
      responses:
        200:
          $ref: '#/components/responses/200Status'
        400:
          $ref: '#/components/responses/400BadRequest'
components:
  schemas:
    Status:
      description:
        Example Status
      type: object
      properties:
        server_ref:
          type: string
          description:
            example
      required:
        - server_ref
  responses:
    400BadRequest:
      description: Bad Request
    200Status:
      description: Successful Status Request
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Status'

Command line used for generation

	java -jar tools/${OPENAPIGEN_JAR} generate \
		-i bug.yaml \
		-o bug \
		-g go

Steps to reproduce

Run tool as above.

snippet from api_xxx.go

	if localVarHTTPResponse.StatusCode >= 300 {
		newErr := GenericOpenAPIError{
			body:  localVarBody,
			error: localVarHTTPResponse.Status,
		}
		if localVarHTTPResponse.StatusCode == 200 {
			var v Status
			err = a.client.decode(&v, localVarBody, localVarHTTPResponse.Header.Get("Content-Type"))
			if err != nil {
				newErr.error = err.Error()
				return localVarReturnValue, localVarHTTPResponse, newErr
			}
			newErr.model = v
			return localVarReturnValue, localVarHTTPResponse, newErr
		}
		return localVarReturnValue, localVarHTTPResponse, newErr
	}

Suggest a fix

This looks to be in the original mustache file in the swagger repo. Minimially those branches should be not generated if it is expected that they will be handled by other code. I'm not sure how this is affected by wildcards.

Start with the Go generator and the original Mustache template mentioned in the issue, then reproduce the output using bug.yaml and the provided Java command. Compare the generated api_xxx.go branch for the 200 response with the error handling around it. Done means the generated client no longer contains unreachable response branches while preserving handling for error responses.