search_api-8.x-1.15/src/Plugin/views/filter/SearchApiOptions.php

<?php

namespace Drupal\search_api\Plugin\views\filter;

use Drupal\Core\Form\FormStateInterface;
use Drupal\views\Plugin\views\filter\ManyToOne;

/**
 * Defines a filter for filtering on fields with a fixed set of possible values.
 *
 * @ingroup views_filter_handlers
 *
 * @ViewsFilter("search_api_options")
 */
class SearchApiOptions extends ManyToOne {

  use SearchApiFilterTrait;

  /**
   * {@inheritdoc}
   */
  public function buildOptionsForm(&$form, FormStateInterface $form_state) {
    parent::buildOptionsForm($form, $form_state);

    unset($form['reduce_duplicates']);
  }

  /**
   * {@inheritdoc}
   */
  public function getValueOptions() {
    parent::getValueOptions();

    if ($this->valueOptions === NULL) {
      $this->valueOptions = [];
    }

    return $this->valueOptions;
  }

}