this isn't really how I imagined this. I had expected we would extend the [bucket validation code in riak_core](https://github.com/basho/riak_core/blob/develop/src/riak_core_bucket_props.erl#L42-L45). Now that I see it I'm not too opposed, but at a minimum we need to open an issue to extend [btypes_eqc](https://github.com/basho/riak_core/blob/develop/test/btypes_eqc.erl) or [its successor](https://github.com/basho/riak_core/issues/563) to cover this case.