CustomConverterWrapper source = newInstance(CustomConverterWrapper.class);
HintedOnly hint = newInstance(HintedOnly.class);
hint.setStr(hintStr);
source.addHint(hint);
CustomConverterWrapperPrime dest = mapper.map(source, CustomConverterWrapperPrime.class);
String destHintStr = (String) dest.getNeedsHint().iterator().next();
assertNotNull(destHintStr);
assertEquals(hintStr, destHintStr);
CustomConverterWrapper sourcePrime = mapper.map(dest, CustomConverterWrapper.class);
String sourcePrimeHintStr = ((HintedOnly) sourcePrime.getNeedsHint().iterator().next()).getStr();