private String fileName() {
    StubElement<?> stub = this;
    while ((stub = stub.getParentStub()) != null) {
      if (stub instanceof PsiFileStub) {
        Object psi = stub.getPsi();
        if (psi instanceof PsiFile) {
          VirtualFile file = ((PsiFile)psi).getVirtualFile();
          return file != null ? file.getUrl() : ((PsiFile)psi).getName();
        }
      }
    }

    return "<unknown file>";
  }
private String fileName()