@Override
      public MetricsRecordBuilder addCounter(MetricsInfo arg0, long arg1) {
        target.getMetrics().put(arg0, arg1);
        return this;
      }
Used by outer class to provide a new <code>MetricsRecordBuilder</code>
for a single metrics record.

@param t The record to build.
llap-common/src/test/org/apache/hadoop/hive/llap/metrics/TestReadWriteLockMetrics.java