private static String packageRootTweak(String packageRoot, char ch) {
private static String packageRootTweak(String packageRoot, String tweak) {
  private static String packageRootTweak(String packageRoot, char ch) {    if (!packageRoot.endsWith(",")) throw new RuntimeException("packageRootTweak must be passed a package root ending in comma, not " + packageRoot);    return packageRoot.substring(0, packageRoot.length() - 1) + ch;  }