The example is to show how to send data to IoTDB from a mqtt client.
enable_mqtt_service=true in iotdb-datanode.properties)CREATE DATABASE root.sg and create time timeseries CREATE TIMESERIES root.sg.d1.s1 WITH DATATYPE=DOUBLE, ENCODING=PLAIN.org.apache.iotdb.mqtt.MQTTClient to run the mqtt client and send events to server.