@NotNull
  public static VirtualFile getSchemaFile(@NotNull String url) {
    String location = ((ExternalResourceManagerEx)ExternalResourceManager.getInstance()).getStdResource(url, null);
    assert location != null : "cannot find a standard resource for " + url;

    VirtualFile result = VfsUtilCore.findRelativeFile(location, null);
    assert result != null : "cannot find a schema file for URL: " + url + " location: " + location;

    return result;
  }
@NotNull
  public static VirtualFile getSchemaFile(@NotNull String url)