bp_notifications_get_meta( int $notification_id, string $meta_key = '', bool $single = true )

function bp_notifications_get_meta( $notification_id = 0, $meta_key = '', $single = true ) {
	add_filter( 'query', 'bp_filter_metaid_column_name' );
	$retval = get_metadata( 'notification', $notification_id, $meta_key, $single );
	remove_filter( 'query', 'bp_filter_metaid_column_name' );

	/**
	 * Filters the metadata for a specified notification item.
	 *
	 * @since BuddyPress 2.3.0
	 *
	 * @param mixed  $retval          The meta values for the notification item.
	 * @param int    $notification_id ID of the notification item.
	 * @param string $meta_key        Meta key for the value being requested.
	 * @param bool   $single          Whether to return one matched meta key row or all.
	 */
	return apply_filters( 'bp_notifications_get_meta', $retval, $notification_id, $meta_key, $single );
}