class FieldUiTestHooks

class FieldUiTestHooks {
    
    /**
     * Implements hook_ENTITY_TYPE_access().
     */
    public function fieldConfigAccess(FieldConfigInterface $field) {
        return AccessResult::forbiddenIf($field->getName() == 'highlander');
    }
    
    /**
     * Implements hook_form_FORM_BASE_ID_alter().
     */
    public function formEntityViewDisplayEditFormAlter(&$form, FormStateInterface $form_state) : void {
        $table =& $form['fields'];
        foreach (Element::children($table) as $name) {
            $table[$name]['parent_wrapper']['parent']['#options'] = [
                'indent' => 'Indent',
            ];
            $table[$name]['parent_wrapper']['parent']['#default_value'] = 'indent';
        }
        $table['indent'] = [
            '#attributes' => [
                'class' => [
                    'draggable',
                    'field-group',
                ],
                'id' => 'indent-id',
            ],
            '#row_type' => 'group',
            '#region_callback' => 'field_ui_test_region_callback',
            '#js_settings' => [
                'rowHandler' => 'group',
            ],
            'human_name' => [
                '#markup' => 'Indent',
                '#prefix' => '<span class="group-label">',
                '#suffix' => '</span>',
            ],
            'weight' => [
                '#type' => 'textfield',
                '#default_value' => 0,
                '#size' => 3,
                '#attributes' => [
                    'class' => [
                        'field-weight',
                    ],
                ],
            ],
            'parent_wrapper' => [
                'parent' => [
                    '#type' => 'select',
                    '#options' => [
                        'indent' => 'Indent',
                    ],
                    '#empty_value' => '',
                    '#default_value' => '',
                    '#attributes' => [
                        'class' => [
                            'field-parent',
                        ],
                    ],
                    '#parents' => [
                        'fields',
                        'indent',
                        'parent',
                    ],
                ],
                'hidden_name' => [
                    '#type' => 'hidden',
                    '#default_value' => 'indent',
                    '#attributes' => [
                        'class' => [
                            'field-name',
                        ],
                    ],
                ],
            ],
        ];
    }

}