bp_get_message_get_recipient_usernames()

	function bp_get_message_get_recipient_usernames() {

		// Sanitized in bp-messages-filters.php.
		$recipients = isset( $_GET['r'] )
			? $_GET['r']
			: '';

		/**
		 * Filters the recipients usernames for prefilling the 'To' field on the Compose screen.
		 *
		 * @since BuddyPress 1.0.0
		 *
		 * @param string $recipients Recipients usernames for 'To' field prefilling.
		 */
		return apply_filters( 'bp_get_message_get_recipient_usernames', $recipients );
	}