void successfulWrite(int numBytes) {
        setTimeToFirstByteFirstTime();

        metric.add(MetricDefinitions.NUM_SUCCESSFUL_WRITES, 1, context);
        metric.set(MetricDefinitions.NUM_BYTES_SENT, numBytes, context);
    }
Responsible for metric reporting for JDisc http request handler support.
@author Tony Vaagenes
container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/RequestMetricReporter.java