Should be able to roundtrip trough serialization. Also nice for debug
and logging purposes where you might want more details than what the
__tostring method provides.
We don't expose the policies directly, to force people to go through :may().
However, there are times when we really just need to know what policies a
role has inside it (e.g. for reporting or debugging purposes).
Previously, if the first inherited role had no opinion, it returned false and
prevented further consultation of other inherited roles.
This bug was found thanks to the implementation of missing test cases
identified through mutation testing.
