public final class ShapesIntersection implements Maybe<Rectangle> {
    public ShapesIntersection(Shape a, Shape b) {
        this.a = a;
        this.b = b;
    }

    @Override
    public boolean isPresent() {
        // find out if shapes intersect
    }

    @Override
    public Rectangle get() {
        // find the common piece of two shapes
    }
}

public inteface Maybe<T> {
    T get();
    boolean isPresent();
    default Optional<T> asOptional() {
       return isPresent() ?
           Optional.of(get()) :
           Optional.empty();
    }
}