build method

Implementation

AuthorizationHeader build() {
  if (_signatureMethod == null) {
    throw StateError('signatureMethod is not set');
  }
  if (_clientCredentials == null) {
    throw StateError('clientCredentials is not set');
  }
  if (_method == null) {
    throw StateError('method is not set');
  }
  if (_url == null) {
    throw StateError('url is not set');
  }
  return AuthorizationHeader(_signatureMethod!, _clientCredentials!,
      _credentials, _method!, _url!, _additionalParameters);
}