@Override
  public void onFileEnabled(final VirtualFile file) {
    ++ fileCount;

    if (sameExtensionCase) {
      final String extension = file.getExtension();
      if (extension == null) {
        sameExtensionCase = false;
      } else if (commonExtension == null) {
        commonExtension = extension;
      } else {
        sameExtensionCase &= commonExtension.equals(extension);
      }
    }

    final VirtualFile parentVirtualFile = file.getParent();

    if (parentVirtualFile != null) {
      Set<String> namesList = folders.get(parentVirtualFile);
      if (namesList == null) {
        namesList = new HashSet<>();
        folders.put(parentVirtualFile, namesList);
      }
      namesList.add(file.getName());
    }
  }
@Override
  public void onFileEnabled(final VirtualFile file)