Add error_prone_core for Dubbo

- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.

## Describe the proposal

The issue names error_prone_core but provides no files, tests, configuration details, or acceptance criteria. Start by locating Dubbo's build configuration and existing dependency-management conventions, then determine the intended Error Prone integration and how it should be validated; the work is done when the agreed configuration is in place and the relevant build checks pass.

Written by the indexing model from the issue text.