While this is generally unsafe, we have to do something for
`CandidateRouteHop`, which is passed to the scorer. Because its
incredibly performance-sensitive, forcing the bindings users to
take a performance hit just to make the scoring interface marginally
safer seems like a bad trade-off.

The fields themselves are already public, so there's not a lot of
value for C users for these, but it avoids having to have this
logic written out by hand in the Java bindings, which is nice.