public async Task <String> ValidateAsync(String input) { String validationMessage = null; if (!String.IsNullOrWhiteSpace(input)) { var query = new ArtifactQueries(); var clientQueryResult = await query.GetClientAsync(_apiOptions, _clientRepository, input); if (clientQueryResult.Success && clientQueryResult.Results.Count > 0) { _callback(new Client(clientQueryResult.Results[0].Artifact.ArtifactID)); } else { validationMessage = String.Format(Constant.Messages.Violations.ClientDoesntExist, input); } } return(validationMessage); }