@Override
 public KnownIdentities save(KnownIdentities entity) {
   if (entity.getId() == null) {
     entity.setId(aggregateIdGenerator.incrementAndGet());
   }
   for (Identity identity : entity.getKnownIdentities()) {
     if (identity.getId() == null) {
       identity.setId(identityIdGenerator.incrementAndGet());
     }
   }
   aggregateMap.put(entity.getId(), entity);
   return entity;
 }