@Override
  public void updateDeleteBatch(long t) {
    deleteBatchHisto.add(t);
  }
Yes this is a get function that doesn't return anything. Thanks Hadoop for breaking all
expectations of java programmers. Instead of returning anything Hadoop metrics expects
getMetrics to push the metrics into the collector.
@param metricsCollector Collector to accept metrics
@param all              push all or only changed?
hbase-hadoop-compat/src/main/java/org/apache/hadoop/hbase/regionserver/MetricsRegionServerSourceImpl.java