Optional-expectation annotations which have an actual counterpart should
have never been serialized to the kotlin_module's proto. See for example
the original (correct) implementation in the old JVM backend in
`PackageCodegenImpl.addDescriptorToOptionalAnnotationsIfNeeded`.
#KT-55611 Fixed
Instead of generating these annotation classes as package-private on
JVM, serialize their metadata to the .kotlin_module file, and load it
when compiling dependent multiplatform modules.
The problem with generating them as package-private was that
kotlin-stdlib for JVM would end up declaring symbols from other
platforms, which would include some annotations from package
kotlin.native. But using that package is discouraged by some tools
because it has a Java keyword in its name. In particular, jlink refused
to work with such artifact altogether (KT-21266).
#KT-38652 Fixed
Alexander Udalov