@Override
        public String toString() {
            return "Sample(" +
                "value=" + value +
                ", eventCount=" + eventCount +
                ", startTimeMs=" + startTimeMs +
                ", lastEventMs=" + lastEventMs +
                ", initialValue=" + initialValue +
                ')';
        }
A SampledStat records a single scalar value measured over one or more samples. Each sample is recorded over a
configurable window. The window can be defined by number of events or elapsed time (or both, if both are given the
window is complete when <i>either</i> the event count or elapsed time criterion is met).
<p>
All the samples are combined to produce the measurement. When a window is complete the oldest sample is cleared and
recycled to begin recording the next sample.

Subclasses of this class define different statistics measured using this basic pattern.
clients/src/main/java/org/apache/kafka/common/metrics/stats/SampledStat.java