final String name = "defMM";
config.getMultiMapConfig(name).setValueCollectionType(MultiMapConfig.ValueCollectionType.SET);
final int insCount = 4;
TestHazelcastInstanceFactory factory = createHazelcastInstanceFactory(insCount);
final HazelcastInstance[] instances = factory.newInstances(config);
TransactionContext context = instances[0].newTransactionContext();
try {
context.beginTransaction();
TransactionalMultiMap mm = context.getMultiMap(name);
assertEquals(0, mm.get("key1").size());