@NotNull
  protected static VirtualFile getTopLevelVirtualFile(@NotNull FileViewProvider fileViewProvider) {
    VirtualFile file = fileViewProvider.getVirtualFile();
    if (file instanceof VirtualFileWindow) file = ((VirtualFileWindow)file).getDelegate();
    return file;
  }
@NotNull
  protected static VirtualFile getTopLevelVirtualFile(@NotNull FileViewProvider fileViewProvider)