onHandshake(data) {
        this.emitReserved("handshake", data);
        this.id = data.sid;
        this.transport.query.sid = data.sid;
        this.upgrades = this.filterUpgrades(data.upgrades);
        this.pingInterval = data.pingInterval;
        this.pingTimeout = data.pingTimeout;
        this.maxPayload = data.maxPayload;
        this.onOpen();
        // In case open handler closes socket
        if ("closed" === this.readyState)
            return;
        this.resetPingTimeout();
    }
Called upon handshake completion.

@param {Object} data - handshake obj
@api private