Form_Edit_Page_Handler::save_elements( array $elements, array $mappings, WP_Error $errors )

	private function save_elements( $elements, $mappings, $errors ) {
		$element_manager = $this->form_manager->get_child_manager( 'containers' )->get_child_manager( 'elements' );

		foreach ( $elements as $id => $data ) {
			if ( empty( $data['container_id'] ) || ! isset( $mappings['containers'][ $data['container_id'] ] ) ) {
				continue;
			}

			$data['container_id'] = $mappings['containers'][ $data['container_id'] ];

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

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

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

		return $mappings;
	}