MongoDbeReplicaSet configuration uses a separate builder for configuration, the newly added method withStartupTimeout should be configured via a method on the Builder and propagated to the underlaying MongoDbContainer

MongoDBReplicaSet does not represent a container so the different structure compared to TC classes is not a problem there. For The MongoDbContainer it is true that it unfortunately doesn't adhere the the fluent builder pattern of TC containers, however at this point consistency is more important – the alternative is a larger refactoring, which probably doesn't have much of added value.