Summary

Currently the HashRouter flags are all just integers: https://github.com/XRPLF/rippled/blob/develop/src/xrpld/app/misc/HashRouter.h#L34-L45

They should be refactored to an enum instead, so that it's easier to validate that they don't clash with other flags or anything else (if they were, you would need explicit type-casting in those places). Since they are currently just ints, this is difficult to do.