OptionalBorderBinaryFunction
class OptionalBorderBinaryFunction<A, OA : ObservableValue<A>, B, OB : ObservableValue<B>>(argA: OA, argB: OB, lambda: (A, B) -> Border?) : BinaryFunction<Border?, A, OA, B, OB> , ObservableOptionalBorder
Boilerplate which avoids having to use generics.
Similar to BorderBinaryFunction, but the value can also be null.