svoid test_restructure_syncMRUCache() {
  new MRUCache o;
  o.maxSize = 5;
  o.put("a", true);
  print(structure(synchronizedMap(o)));
  Map o2 = cast restructure(o);
  assertEqualsVerbose(ll(pair("a", true)), mapToPairs(o2));
  assertEqualsVerbose(5, ((MRUCache) unwrapSynchronizedMap(o2)).maxSize);
}

Began life as a copy of #1024862