I had a problem with that at some point, but now `accept()` should only throw an exception if the user said he wanted to match `PutKeyValueCommand`s and tried to match the cache name (or a key name for a `PrepareCommand`). I'd say that's fine, because that would be a user error. 

To be fair, it would be nicer to check that `commandClass` extends `DataCommand`/`CacheRpcCommand` in the constructor, but I don't think it's a big issue. And matching the keys in a `PrepareCommand` may also be nice for some tests, but I had to stop somewhere...