@NotNull
    IntSet getAllContainingFileIds(@NotNull CompilerRef ref) throws StorageException {
      return InvertedIndexUtil
        .collectInputIdsContainingAllKeys(myIndex.get(JavaCompilerIndices.BACK_USAGES),
                                          Collections.singletonList(ref),
                                          null,
                                          null);
    }
@NotNull
    IntSet getAllContainingFileIds(@NotNull CompilerRef ref)