@Override
                public void onException(Throwable e) {
                    LOGGER.error("exception caught", e);
                    if (e instanceof OverflowException) {
                        overflow = true;
                    }
                    resendEvent(es);
                }
fetch message, wait if queue is empty

@return EventStat
@throws Exception
inlong-tubemq/tubemq-connectors/tubemq-connector-flume/src/main/java/org/apache/flume/sink/tubemq/TubemqSink.java