Follow this checklist to help us incorporate your contribution quickly and easily. Notice, `it would be helpful if you could finish the following 5 checklist(the last one is not necessary)before request the community to review your PR`.
-[x] Make sure there is a [Github issue](https://github.com/apache/rocketmq/issues) filed for the change (usually before you start working on it). Trivial changes like typos do not require a Github issue. Your pull request should address just this issue, without pulling in other changes - one PR resolves one issue.
- [x] Format the pull request title like `[ISSUE #123] Fix UnknownException when host config not exist`. Each commit in the pull request should have a meaningful subject line and body.- [x] Write a pull request description that is detailed enough to understand what the pull request does, how, and why.-[x] Write necessary unit-test(over 80% coverage) to verify your logic correction, more mock a little better when cross module dependency exist. If the new feature or significant change is committed, please remember to add integration-test in [test module](https://github.com/apache/rocketmq/tree/master/test).- [x] Run `mvn -B clean apache-rat:check findbugs:findbugs checkstyle:checkstyle` to make sure basic checks pass. Run `mvn clean install -DskipITs` to make sure unit-test pass. Run `mvn clean test-compile failsafe:integration-test` to make sure integration-test pass.
