Drupal → Как создать свой составной элемент формы

<?php
 
namespace Drupal\modulename\Element;
 
use Drupal\Core\Form\FormStateInterface;
use Drupal\Core\Render\Element\FormElement;
 
/**
 * @FormElement("fullname")
 */
class FullnameElement extends FormElement {
 
  /**
   * {@inheritDoc}
   */
  public function getInfo() {
    $class = get_class($this);
 
    return [
      '#input' => TRUE,
      '#process' => [
        [$class, 'processElement'],
      ],
      '#theme_wrappers' => ['form_element'],
    ];
  }
 
  /**
   * Element process callback.
   */
  public static function processElement(array &$element, FormStateInterface $form_state, array &$complete_form) {
    $element['#tree'] = TRUE;
 
    $element['surname'] = [
      '#type' => 'textfield',
      '#title' => t('Surname'),
      '#default_value' => $element['#default_value']['surname'] ?? '',
    ];
 
    $element['firstname'] = [
      '#type' => 'textfield',
      '#title' => t('Firstname'),
      '#default_value' => $element['#default_value']['firstname'] ?? '',
    ];
 
    $element['middlename'] = [
      '#type' => 'textfield',
      '#title' => t('Middlename'),
      '#default_value' => $element['#default_value']['middlename'] ?? '',
    ];
 
    return $element;
  }
 
}

$form['contact_information'] = [
  '#type' => 'fullname',
  '#title' => t('Contact information'),
];