This message was deleted.

map it to another list?

val t = s.map { it.filterNotNull() }
println(t.get())

Nope, this code will throw an exception:

Cannot query the value of this property because it has no value available.

Which matches the documentation of `add`:

This property will have no value when the given provider has no value.

.

oh that's where the problem is, I see

I use the following workaround to optionally add a provider to a list provider:

s.addAll(providers.provider {null}.map {listOf(it)}.orElse(emptyList()))