message: return promise for promisable object property in case the property not available.
diff: @@ -95,7 +95,7 @@ export function promisable(params: IPromisableParam): any {
  else {
  let id = "";
  if (!this[params.targetKey]) {
  - Q.when({});
  + return Q.when({});
  }
  if (Utils.isBasonOrStringType(this[params.targetKey])) {
  id = this[params.targetKey];
  