* @param <V4> the type returned by the fourth future
     * @param <V5> the type returned by the fifth future
     * @param <U> the type returned by the function
     */
    public interface ClosingFunction5<
        V1 extends @Nullable Object,
        V2 extends @Nullable Object,
        V3 extends @Nullable Object,
        V4 extends @Nullable Object,
        V5 extends @Nullable Object,