code: func InvalidContentType(detail string, a ...interface{}) *ProblemDetails {
  	return &ProblemDetails{
  		Type:       MalformedProblem,
  		Detail:     fmt.Sprintf(detail, a...),
  		HTTPStatus: http.StatusUnsupportedMediaType,
  	}
  }
docs: // InvalidContentType returns a ProblemDetails suitable for a missing
  // ContentType header, or an incorrect ContentType header