static L<Byte> wrapByteArrayAsList (byte[] l) {
  ret new RandomAccessAbstractList<Byte>() {
    public int size() { ret l.length; }
    public Byte get(int i) { ret l[i]; }
    public Byte set(int i, Byte val) {
      Byte a = l[i];
      l[i] = val;
      ret a;
    }
  };
}

Began life as a copy of #1029408