private static boolean isEquals(@Nullable ContentRevision revision1, @Nullable ContentRevision revision2) {
    if (Comparing.equal(revision1, revision2)) return true;
    if (revision1 instanceof CurrentContentRevision && revision2 instanceof CurrentContentRevision) {
      VirtualFile vFile1 = ((CurrentContentRevision)revision1).getVirtualFile();
      VirtualFile vFile2 = ((CurrentContentRevision)revision2).getVirtualFile();
      return Comparing.equal(vFile1, vFile2);
    }
    return false;
  }
private static boolean isEquals(@Nullable ContentRevision revision1, @Nullable ContentRevision revision2)