applyToParams method
Apply authentication settings to header and query params.
Implementation
@override
void applyToParams(
    List<QueryParam> queryParams, Map<String, String> headerParams) {
  if (_accessToken is String) {
    headerParams['Authorization'] = 'Bearer $_accessToken';
  } else if (_accessToken is HttpBearerAuthProvider) {
    headerParams['Authorization'] = 'Bearer ${_accessToken()}';
  } else {
    throw ArgumentError(
        'Type of Bearer accessToken should be a String or a String Function().');
  }
}