protected @Nullable Color getFallbackColor(@NotNull ColorKey fallbackKey) {
    ColorKey cur = fallbackKey;
    while (true) {
      Color color = getDirectlyDefinedColor(cur);
      if (color == NULL_COLOR_MARKER) return null;
      ColorKey next = cur.getFallbackColorKey();
      if (color != null && (color != INHERITED_COLOR_MARKER || next == null)) {
        return color;
      }
      if (next == null) {
        return null;
      }
      cur = next;
    }
  }
protected @Nullable Color getFallbackColor(@NotNull ColorKey fallbackKey)