Android plugin fails to find Java class

I’m updating a Android plugin from 4.19 to 4.24 which has gone fine, but now when I actually try to run the APK, the Android lib tries to fetch the java class and fails to get the class - I really haven’t changed the APL code and I can see both the java class and the so files get copied to the correct location, but it seems unable to find the class - previously I’d see the class name in the generated dex file, but it’s not in there now. Any suggestions on issues that could cause this behavior?

So it turns out that I’ve got the java files specified in the prebuildCopies section, and they do get copied (so says the logging). But at some point they get deleted from the intermediate directory. Had the files copied to non-UE4 dir and I do see them show up there, so something in the build process is deciding that they aren’t needed and is deleting them.