code: func ConnectionFailure(detail string, a ...interface{}) *ProblemDetails {
  	return &ProblemDetails{
  		Type:       ConnectionProblem,
  		Detail:     fmt.Sprintf(detail, a...),
  		HTTPStatus: http.StatusBadRequest,
  	}
  }
docs: // ConnectionFailure returns a ProblemDetails representing a ConnectionProblem
  // error