@Override
  public int getActiveWriteRpcHandlerCount() {
    return 0;
  }
Users of the hbase.region.server.rpc.scheduler.factory.class customization config can return an
implementation which extends this class in order to minimize impact of breaking interface
changes.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/DelegatingRpcScheduler.java