Golang Generated api client does not work for plain text body types

[Vad1mo]

Description

The Generated API Client for GoLang does not work properly for plain string body types.

The error message is: Invalid body type text/plain

Swagger-codegen version

2.3.1

Swagger declaration file content or url

/Token/:
    post:
      operationId: Token
      consumes:
        - text/plain
      responses:
        '200':
          description: OK
          schema:
           type: string
        '400':
          description: Bad Request
          schema:
            type: string
      produces:
        - "application/json"
        - "text/json"
      parameters:
        - in: body
          name: body
          description: The Grand Type
          schema:
            type: string

Steps to reproduce

Api_client.go

func setBody(body interface{}, contentType string) (bodyBuf *bytes.Buffer, err error) {
	if bodyBuf == nil {
		bodyBuf = &bytes.Buffer{}
	}

	if reader, ok := body.(io.Reader); ok {
		_, err = bodyBuf.ReadFrom(reader)
	} else if b, ok := body.([]byte); ok {
		_, err = bodyBuf.Write(b)
	} else if s, ok := body.(string); ok {  // <<--
		_, err = bodyBuf.WriteString(s)
	} else if jsonCheck.MatchString(contentType) {
		err = json.NewEncoder(bodyBuf).Encode(body)
	} else if xmlCheck.MatchString(contentType) {
		xml.NewEncoder(bodyBuf).Encode(body)
	}

	if err != nil {
		return nil, err
	}

	if bodyBuf.Len() == 0 {
		err = fmt.Errorf("Invalid body type %s\n", contentType)
		return nil, err
	}
	return bodyBuf, nil
}

Suggest a fix/enhancement

The check should be changed from `body.(string); ok
The body is an interface containing the pointer to the string.

	} else if s, ok := body.(*string); ok {
		_, err = bodyBuf.WriteString(*s)

[HugoMario]

fixed by #7987