code: @Override
      public void validate() throws OpsGenieClientValidationException {
          super.validate();
          if (getAlias() == null)
              throw OpsGenieClientValidationException.missingMandatoryProperty(OpsGenieClientConstants.API.ALIAS);
      }
docs: check the parameters for validation.
  
  @throws OpsGenieClientValidationException when alias is null!