package errhttp type PayloadTooLarge interface { ClientError PayloadTooLarge() } type internalPayloadTooLarge struct { err error } func PayloadTooLargeWrap(err error) error { return internalPayloadTooLarge{ err:err, } } func (receiver internalPayloadTooLarge) Error() string { return receiver.err.Error() } func (receiver internalPayloadTooLarge) Err() error { return receiver.err } func (internalPayloadTooLarge) ClientError() { // Nothing here. } func (internalPayloadTooLarge) PayloadTooLarge() { // Nothing here. }