private Iterable<AbstractFileViewProvider> getKnownCopies() {
    Set<AbstractFileViewProvider> copies = getUserData(KNOWN_COPIES);
    if (copies != null) {
      return JBIterable.from(copies).filter(copy -> copy.getCachedPsiFiles().stream().anyMatch(f -> f.getOriginalFile().getViewProvider() == this));
    }
    return Collections.emptySet();
  }
private Iterable<AbstractFileViewProvider> getKnownCopies()