Thanks for your interest!
I'm not exactly sure what you mean by "in case any of the JSpecify annotations aren't compiled with". But if you mean to ask about a plugin that checks your code for correctness given an annotated library, or if your code itself is null marked, then the plan is for existing tools, such as EISOP, NullAway, and others, to understand the semantics of these annotations. Those tools already have Maven plugins for integrating into your build, and once they correctly understand the JSpecify annotations, they'll work much better with third-party libraries that adopt them.
Let me know if I've understood your question correctly.