public function __construct( $parent_post_type ) {
    $this->parent_post_type = $parent_post_type;
    $post_type_object       = get_post_type_object( $parent_post_type );
    $parent_controller      = $post_type_object->get_rest_controller();

    if ( ! $parent_controller ) {
      $parent_controller = new WP_REST_Posts_Controller( $parent_post_type );
    }

    $this->parent_controller = $parent_controller;

    $revisions_controller = $post_type_object->get_revisions_rest_controller();
    if ( ! $revisions_controller ) {
      $revisions_controller = new WP_REST_Revisions_Controller( $parent_post_type );
    }
    $this->revisions_controller = $revisions_controller;
    $this->rest_base            = 'autosaves';
    $this->parent_base          = ! empty( $post_type_object->rest_base ) ? $post_type_object->rest_base : $post_type_object->name;
    $this->namespace            = ! empty( $post_type_object->rest_namespace ) ? $post_type_object->rest_namespace : 'wp/v2';
  }