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

Began life as a copy of #1035682