As we didn't find any solution for the problems we had with builders (RT-24272), we decided to deprecate them and freeze them in the state from 2.2 version (RT-30520). This should be documented in release notes and we should also provide a migration strategy for the people, who are using builders now.
(Once such text is written, the builders javadoc should be updated to contain link to it (as part of RT-30520).)