mapEachNotNullTo
inline fun <T, R : Any, C : MutableCollection<in R>> Provider<Collection<T>>.mapEachNotNullTo(crossinline makeCollection: (size: Int) -> C, crossinline transform: (T) -> R?): Provider<C>
Creates and returns a new Provider that maps each element of the Collection obtained from this using the transform function and filters out all null results. The results are added to a collection created by makeCollection.
makeCollection and transform should be pure functions.
The returned provider will only be stored in a WeakReference in the parent provider (this).