@Override
  public long getPeriodicalFlushTimeout(TimeUnit unit) {
    return unit.convert(periodicFlushTimeoutNs, TimeUnit.NANOSECONDS);
  }
The implementation of {@link AsyncBufferedMutator}. Simply wrap an {@link AsyncTable}.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncBufferedMutatorImpl.java