Just wondering, when did they do that? From all I found in their Terms and Conditions, they only disallow the selling of cape cosmetics, but there's no mention of not being allowed to make mods involving them (as long as they aren't sold).
Yes. It should be LazyOptional<T>. Note that <T> here is still the type of the capability, so you'll get back a LazyOptional<IItemHandler>. Which you can then call ifPresent() on and pass in a lambda that gets executed if the capability is indeed present (non-null) or you can do something like OrElse(null) and null check (prefer using ifPresent) or use OrElseThrow().
I never put a license in my git repos because I never know what to license it as.
I have no qualms with people looking at my code to figure out how I did what I did, or even borrowing sections (enjoy the loot func!). Its the "copy and redistribute large portions" that I don't appreciate.