class Value {
    private /*@ spec_public @*/ boolean value;

    /*@ ensures value == v; @*/
    public Value(boolean v) {
	value = v;
    }
    
    /*@ ensures value == !\old(value); @*/
    public void toggle() {
	value = !value;
    }

    /*@ ensures \result == value; @*/
    public boolean get() {
	return value;
    }
}

class Broken {
    /*@ private invariant obj.value == true; @*/

    private /*@ non_null @*/ Value obj;

    public Broken() {
	obj = new Value(true);
    }

    /*@ requires o.value == true; @*/
    public Broken(/*@ non_null @*/ Value o) {
	obj = o;
    }

    /*@ ensures \result == true; @*/
    public boolean getValue() {
	return obj.get();
    }
}

public class Invariant1 {
    public static void main(String[] param) {
	Value val = new Value(true);
	Broken broken = new Broken(val);
	val.toggle();

	if (!broken.getValue()) {
	    throw new RuntimeException("ESC/Java is unsound!");
	}
    }
}