Eclipse Compiler including annotation processing (classes with inner classes)

This post is a follow up from the post https://intellij-support.jetbrains.com/hc/en-us/community/posts/4417393355666-Eclipse-Compiler-including-annotation-processing

Topic is that annotation processing of classes with the ejc compiler isn't working, but only when a class contains an inner class.

the error message is exactly the same like in the post mentioned above https://intellij-support.jetbrains.com/hc/en-us/community/posts/4417393355666-Eclipse-Compiler-including-annotation-processing

to reproduce this issue you can checkout https://github.com/mbauhardt/ecj-filer-exception to reproduce.