Form_Edit_Page_Handler::save_containers( array $containers, array $mappings, WP_Error $errors )

	private function save_containers( $containers, $mappings, $errors ) {
		$container_manager = $this->form_manager->get_child_manager( 'containers' );

		foreach ( $containers as $id => $data ) {
			$data['form_id'] = key( $mappings['forms'] );

			if ( $this->is_temp_id( $id ) ) {
				$container = $container_manager->create();
			} else {
				$container = $container_manager->get( $id );
				if ( ! $container ) {
					$container = $container_manager->create();
				}
			}

			foreach ( $data as $key => $value ) {
				$container->$key = $value;
			}

			$status = $container->sync_upstream();
			if ( is_wp_error( $status ) ) {
				$errors->add( $status->get_error_code(), $status->get_error_message(), array(
					'id'   => $id,
					'data' => $data,
				) );
			} else {
				$mappings['containers'][ $id ] = $container->id;
			}
		}

		return $mappings;
	}