composeAsync

Source

static AsyncValidatorFn composeAsync(List<AsyncValidatorFn> validators) {
  if (validators == null) return null;
  var presentValidators = validators.where((v) => v != null).toList();
  if (presentValidators.length == 0) return null;
  return (model_module.AbstractControl control) {
    var promises =
        _executeAsyncValidators(control, presentValidators).map(_toFuture);
    return Future.wait(promises).then(_mergeErrors);
  };
}