Restoring predicate consistency by removing 'Validated' and adding 'Notnull'.

[apollyon4]

I removed @Validated from all predicates because it wasn't working.
Added @NotNull to BeforeRoutePredicateFactory.Config similar to AfterRoutePredicateFactory.

And I added some tests to verify correct behavior before and after removing @Validated and adding @NotNull.

This is a PR for the #3478 issue.

[apollyon4]

While working on the predicates, I thought that if there’s no intention to configure the PathRoutePredicateFactory, HostRoutePredicateFactory, and MethodRoutePredicateFactory in a meaningful way, there’s no real reason to include them. Therefore, I think a null check for them would be necessary.