com.intellij.psi.PsiAnnotation not found

I'm trying to update a plugin (intellij-lsp) that has gone a bit stale, mainly to use as a jumping-off point for creating a new LSP-based plugin for Julia language support. One class makes reference to com.intellij.psi.PsiAnnotation and com.intellij.psi.PsiAnnotationOwner, but I can't find these classes anywhere. Where have they gone?

Thanks,

-Randy