public Employee Authenticate(Credential credential)
 {
     try
     {
         var result = _manager.Authenticate(CredentialTranslator.ToDomainModel(credential));
         if (result == null)
         {
             return(null);
         }
         return(result.ToDataContract());
     }
     catch (Exception ex)
     {
         //var rethrow = ExceptionPolicy.HandleException("service.policy", ex);
         //if (rethrow) throw;
         //return null;
         throw ex;
     }
 }