[KSP2] Resolver.getDeclarationsFromPackage() couldn't find Java declarations

This started with 1.0.22 snapshot (1.0.21 was fine). When there is only Java sources in a package `Resolver.getDeclarationsFromPackage()` can't find the declarations in it. But after adding Kotlin source it works fine.

Repro: https://github.com/kuanyingchou/ksp/commit/d150c00eccc14b45422425d6a19d1a830116d915