sendPing(nodeID, id) {
		return this.publish(
			new Packet(P.PACKET_PING, nodeID, {
				time: Date.now(),
				id: id || this.broker.generateUid()
			})
		).catch(
			/* istanbul ignore next */ err => {
				this.logger.error(`Unable to send PING packet to '${nodeID}' node.`, err);

				this.broker.broadcastLocal("$transit.error", {
					error: err,
					module: "transit",
					type: C.FAILED_SEND_PING_PACKET
				});
			}
		);
	}
Send ping to a node (or all nodes if nodeID is null)

@param {String} nodeID
@param {String} id
@returns
@memberof Transit