code.anew().setType(CollectionChangeTrackerImpl.class);
code.dup();
code.aload().setLocal(ret);
code.constant().setValue(allowsDuplicates(type));
code.constant().setValue(isOrdered(type));
code.invokespecial().setMethod(CollectionChangeTrackerImpl.class,
"<init>", void.class, new Class[] { Collection.class,
boolean.class, boolean.class });
code.putfield().setField(changeTracker);
ifins.setTarget(code.aload().setLocal(ret));