Access Repository Informations for PsjFiles

What do you want to do with these annotations? 

For example, you can load them like this (though, it's better not to access vcs from EDT or while holding readLock - so file content might be already changed)
You can use `UpToDateLineNumberProviderImpl` to convert "local line numbers" to "annotated line numbers".

 val virtualFile = psiFile.virtualFile
 val vcs = ProjectLevelVcsManager.getInstance(project).getVcsFor(virtualFile)
 val annotationsProvider = vcs?.annotationProvider
 if (annotationsProvider != null) {
   val fileAnnotations = annotationsProvider.annotate(virtualFile)
   try {
     val affectedInRevision = fileAnnotations.getLineRevisionNumber(12)
     doStuff(fileAnnotations)
   }
   finally {
     fileAnnotations.dispose()
   }
 }

Hello, I want to know the author of the File by counting the Lines by Author.

This part of platform is not really extendable, but the code snippet below should work.
(Keep in mind, that `annotationsProvider.annotate` is a potentially slow operation, up to 30s for big/old files and Win machines.)

val virtualFile = psiFile.virtualFile
val vcs = ProjectLevelVcsManager.getInstance(project).getVcsFor(virtualFile) ?: throw Exception("File is not under VCS")
val annotationsProvider = vcs.annotationProvider ?: throw Exception("VCS does not support annotations")
val fileAnnotations = annotationsProvider.annotate(virtualFile)
try {
  val authors = HashMultiset.create<String>()
  val authorsMapping = fileAnnotations.authorsMappingProvider?.authors ?: throw Exception("VCS does not support extended annotations")
  for (i in 0 until fileAnnotations.lineCount) {
    val revision = fileAnnotations.getLineRevisionNumber(i)
    val author = authorsMapping[revision]
    if (author != null) {
      authors.add(author)
    }
  }
  return authors
}
finally {
 fileAnnotations.dispose()
}