operatorValidate example

if ($this->canExpose()) {
        // Add the subform from buildExposeForm().         $this->showExposeForm($form, $form_state);
      }
    }
  }

  /** * Simple validate handler. */
  public function validateOptionsForm(&$form, FormStateInterface $form_state) {
    $this->operatorValidate($form, $form_state);
    $this->valueValidate($form, $form_state);
    if (!empty($this->options['exposed']) && !$this->isAGroup()) {
      $this->validateExposeForm($form, $form_state);
    }
    if ($this->isAGroup()) {
      $this->buildGroupValidate($form, $form_state);
    }
  }

  /** * Simple submit handler. */