code: private Address allocateAddress(final Definition definition, final Address maybeAddress) {
      final Address address = maybeAddress != null ?
              maybeAddress : world.addressFactory().uniqueWith(definition.actorName());
      return address;
    }
docs: Answers an Address for an Actor. If maybeAddress is allocated answer it; otherwise
  answer a newly allocated Address. (INTERNAL ONLY)
  @param definition the Definition of the newly created Actor
  @param maybeAddress the possible Address
  @return Address