Spicy pizza configurator

PizzaConf.java

import org.chocosolver.solver.Model;
import org.chocosolver.solver.Solver;
import org.chocosolver.solver.constraints.Constraint;
import org.chocosolver.solver.exception.ContradictionException;
import org.chocosolver.solver.variables.BoolVar;
import org.chocosolver.solver.variables.IntVar;

public class PizzaConf {
    Model m = new Model();
    Solver s = m.getSolver();
    final int numBools = 6;
    BoolVar[] toppings = m.boolVarArray(numBools);
    int[] isSpicyCoefficients = new int[numBools];
    IntVar isSpicyPizza = m.intVar("weightedSum", 0, numBools);

    private PizzaConf() {
        for (int i = 0; i < numBools; i++) {
            isSpicyCoefficients[i] = i < 2 ? 1 : 0;
        }
        // is hot indicator
        m.scalar(toppings, isSpicyCoefficients, "=", isSpicyPizza).post();
        // at least one hot topping
        m.arithm(isSpicyPizza, ">=", 1).post();
        m.scalar(toppings, isSpicyCoefficients, ">=", 1).post();
        // max elements selected
        m.sum(toppings, "<=", 3).post();
        System.out.println(">>> init");
        propAndPrint();

        postEqual(2);
        propAndPrint();

        postEqual(3);
        propAndPrint();

        postEqual(1);
        // the following statement causes a contradiction exception:
        // CONTRADICTION (PropXplusYeqZ(BV_1, BV_2, weightedSum), weightedSum = {1..2}) : new lower bound is greater than upper bound
//         postEqual(4);
        propAndPrint();
    }

    private void postEqual(int i) {
        Constraint constraint = m.arithm(toppings[i], "=", 1);
        System.out.println(">>> " + constraint);
        constraint.post();
    }

    private void propAndPrint() {
        try {
            s.propagate();
        } catch (ContradictionException e) {
            throw new RuntimeException(e);
        }
        for (int i = 0; i < numBools; i++) {
            System.out.printf("%-16s %d%n", toppings[i], isSpicyCoefficients[i]);
        }
        System.out.println(isSpicyPizza);
        System.out.println();
    }

    public static void main(String[] args) {
        new PizzaConf();
    }
}