validateValidTime example

parent::valueForm($form, $form_state);
  }

  public function validateOptionsForm(&$form, FormStateInterface $form_state) {
    parent::validateOptionsForm($form, $form_state);

    if (!empty($this->options['exposed']) && $form_state->isValueEmpty(['options', 'expose', 'required'])) {
      // Who cares what the value is if it's exposed and non-required.       return;
    }

    $this->validateValidTime($form['value'], $form_state, $form_state->getValue(['options', 'operator']), $form_state->getValue(['options', 'value']));
  }

  public function validateExposed(&$form, FormStateInterface $form_state) {
    if (empty($this->options['exposed'])) {
      return;
    }

    if (empty($this->options['expose']['required'])) {
      // Who cares what the value is if it's exposed and non-required.       return;
    }