public abstract class Metric {
    @Column(name = "source", tag = true)
    private String source;
}


@Measurement(name = "visitor")
public class Visitor extends Metric {
    @Column(name = "count")
    private long count;
}


public void writeData() {
    InfluxDBClient influxDBClient = ...
    writeApi = influxDBClient.getWriteApi();

    Metric metric = new Visitor();
    ...
    writeApi.writeMeasurement(WritePrecision.S, metric);
}