private static long getRpcCallSize(final CallRunner callRunner) {
    return Optional.ofNullable(callRunner).map(CallRunner::getRpcCall).map(RpcCall::getSize)
      .orElse(0L);
  }
Return the {@link RpcCall#getSize()} from {@code callRunner} or 0L.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/RpcExecutor.java