BP_Messages_Message – BuddyBoss Resources

class BP_Messages_Message {
    public static $last_inserted_id;
    /**
     * ID of the message.
     *
     * @var int
     */
    public $id;
    /**
     * ID of the message thread.
     *
     * @var int
     */
    public $thread_id;
    /**
     * ID of the sender.
     *
     * @var int
     */
    public $sender_id;
    /**
     * Subject line of the message.
     *
     * @var string
     */
    public $subject;
    /**
     * Content of the message.
     *
     * @var string
     */
    public $message;
    /**
     * Date the message was sent.
     *
     * @var string
     */
    public $date_sent;
    /**
     * Message recipients.
     *
     * @var bool|array
     */
    public $recipients = false;
    /**
     * Constructor.
     *
     * @param int|null $id Optional. ID of the message.
     */
    public function __construct( $id = null ) {
        $this->date_sent = bp_core_current_time();
        $this->sender_id = bp_loggedin_user_id();
        if ( ! empty( $id ) ) {
            $this->populate( $id );
        }
    }

Source: BP_Messages_Message – BuddyBoss Resources