@Override
    public @Nullable Set<VirtualFile> findFileIdsWithImplicitToString(@NotNull CompilerRef ref) throws StorageException {
      Set<VirtualFile> result = VfsUtilCore.createCompactVirtualFileSet();
      myIndex.get(JavaCompilerIndices.IMPLICIT_TO_STRING).getData(ref).forEach(
        (id, value) -> {
          final VirtualFile file = findFile(id);
          if (file != null) {
            result.add(file);
          }
          return true;
        });
      return result;
    }
@Override
    public @Nullable Set<VirtualFile> findFileIdsWithImplicitToString(@NotNull CompilerRef ref)