SetItems
set_items(?SetRef, ?Items): converts between a Prolog list Items and an it.unibo.tuprolog.solve.libs.oop.ObjectRef SetRef wrapping a Kotlin/Java Set holding the same (converted, duplicate-free) elements, in either direction -- see AbstractIterableItems.
Example: set_items(S, [1, 2, 2]) binds S to an it.unibo.tuprolog.solve.libs.oop.ObjectRef wrapping setOf(1, 2).