sEntity is comming from input / String - I'm really know only basics of Java but why would You prefer this as enum (TBH I cannot imagine (with my poor language knowledge) how can it be Enum)? And regarding types - it has compiled properly - thank You.
sEntity should really be an enum.
As for the type, ent needs to be the most common supertype of all of the possibilities. In the case you've shown that is MonsterEntity, so it would be Class<? extends MonsterEntity> and monsters would be List<? extends MonsterEntity>.
I dont use edge but im fairly certain that if you go to the settings you will find an option that prevents saying that, (im guessing) i use chrome and there a message like that pops up and u can press continue with no problem