public Timer createTimer() {
        return new Timer(this);
    }
A histogram samples observations (usually things like request durations or response sizes) and counts them in
configurable buckets. It also provides a sum of all observed values.
oap-server/server-telemetry/telemetry-api/src/main/java/org/apache/skywalking/oap/server/telemetry/api/HistogramMetrics.java