private static @NotNull Key<String> getOrCreateProjectKey(@NotNull Project project) {
    Key<String> key = PROJECT_KEY_FOR_SUBSTITUTED_LANG_KEY.get(project);
    if (key == null) {
      synchronized (PROJECT_KEY_FOR_SUBSTITUTED_LANG_KEY) {
        key = PROJECT_KEY_FOR_SUBSTITUTED_LANG_KEY.get(project);
        if (key == null) {
          key = new Key<>("Substituted lang key for " + project.getName());
          PROJECT_KEY_FOR_SUBSTITUTED_LANG_KEY.set(project, key);
        }
      }
    }
    return key;
  }
private static @NotNull Key<String> getOrCreateProjectKey(@NotNull Project project)