The One-Time 0-1 Option: Maybe

Maybe is an RxJava type for cases where you may get a result, or you may not, or you may get an error.

For the case where you might get a row or you might not, and you would prefer not to have to look for a special exception to identify the zero-rows case, Maybe is a fine choice:

@Query("SELECT * FROM trips WHERE id=:id")
Maybe<Trip> maybeTripById(String id);