svoid test_restructure_syncLinkedList() {
  LS orig = synchronizedList(litlinkedlist("a", "b"));
  print(structure(orig));
  LS ll = cast restructure(orig);
  assertEquals(orig.getClass(), ll.getClass());
  assertTrueVerbose(unwrapSynchronizedList(ll) instanceof LinkedList);
  assertEqualsVerbose(orig, ll);

  // legacy format
  L l2 = cast unstructure("syncLL[1, 2]");
  assertEquals(synchronizedList(litlinkedlist()).getClass(), l2.getClass());
  assertTrue(unwrapSynchronizedList(l2) instanceof LinkedList);
  assertEquals(ll(1, 2), l2);

}

Began life as a copy of #1023894