public static BufferCallBeforeInitHandler.BufferCallEvent fail(IOException error) {
      return new BufferCallEvent(BufferCallAction.FAIL, error);
    }
We will expose the connection to upper layer before initialized, so we need to buffer the calls
passed in and write them out once the connection is established.
hbase-client/src/main/java/org/apache/hadoop/hbase/ipc/BufferCallBeforeInitHandler.java