ContactFormListBuilder.php

<?php

namespace Drupal\contact;

use Drupal\Core\Config\Entity\ConfigEntityListBuilder;
use Drupal\Core\Entity\EntityInterface;

/**
 * Defines a class to build a listing of contact form entities.
 *
 * @see \Drupal\contact\Entity\ContactForm
 */
class ContactFormListBuilder extends ConfigEntityListBuilder {
  
  /**
   * {@inheritdoc}
   */
  public function buildHeader() {
    $header['form'] = $this->t('Form');
    $header['recipients'] = $this->t('Recipients');
    $header['selected'] = $this->t('Selected');
    return $header + parent::buildHeader();
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildRow(EntityInterface $entity) {
    // Special case the personal form.
    if ($entity->id() == 'personal') {
      $row['form'] = $entity->label();
      $row['recipients'] = $this->t('Selected user');
      $row['selected'] = $this->t('No');
    }
    else {
      $row['form'] = $entity->toLink(NULL, 'canonical')
        ->toString();
      $row['recipients']['data'] = [
        '#theme' => 'item_list',
        '#items' => $entity->getRecipients(),
        '#context' => [
          'list_style' => 'comma-list',
        ],
      ];
      $default_form = \Drupal::config('contact.settings')->get('default_form');
      $row['selected'] = $default_form == $entity->id() ? $this->t('Yes') : $this->t('No');
    }
    return $row + parent::buildRow($entity);
  }

}