private void doBadPreambleHandling(String msg, Exception e) throws IOException {
    RpcServer.LOG.warn(msg, e);
    doRespond(getErrorResponse(msg, e));
  }
Has the request header and the request param and optionally encoded data buffer all in this one
array.
<p/>
Will be overridden in tests.
hbase-server/src/main/java/org/apache/hadoop/hbase/ipc/ServerRpcConnection.java