You may want to declare a multi-binding but provide no values. This is useful for cases where you want to 'extend' the set provided. Right now this is not possible because you have to declare at least one @IntoMap or @IntoSet in order for it to not complain that it can't provide the value. Dagger has 2 ways around this:

Add @Multibinds to the provider

@Multibinds abstract fun aSet(): Set<Foo>

Provide an empty collection with @ElementsIntoSet

@Provides @ElementsIntoSet
fun primeEmptyFooSet(): Set<Foo> = emptySet()