Not keen on the way the constructor takes an `EntityLocal` which if it's not a MongoDBServer then it will guaranteed ClassCastException here. Unfortunately there's not a common interface for EntityLocal and MongoDBServer, so only the class would do both. I'd reluctantly change the constructor to take a `MongoDBServerImpl` rather than an `EntityLocal`, and also override `getEntity()` to return a MongoDBServer so you can do the cast there. I think that's clearer than casting inside `launch()` and any other methods that need it.