private static @Nullable EditorColorsScheme getBaseDefaultScheme(@NotNull EditorColorsScheme scheme) {
    if (!(scheme instanceof AbstractColorsScheme)) {
      return null;
    }
    if (scheme instanceof DefaultColorsScheme) {
      return scheme;
    }
    EditorColorsScheme parent = ((AbstractColorsScheme)scheme).parentScheme;
    return parent != null ? getBaseDefaultScheme(parent) : null;
  }
private static @Nullable EditorColorsScheme getBaseDefaultScheme(@NotNull EditorColorsScheme scheme)