public function setup_fields() {
		if ( ! function_exists( 'register_rest_field' ) ) {
			return;
		}

		$post_types = papi_get_post_types();

		foreach ( $post_types as $post_type ) {
			register_rest_field( $post_type, 'page_type', [
				'get_callback' => [$this, 'get_page_type']
			] );
		}
	}