@Override
    public String toString() {
        return "Rule{" +
               "andConditions=" + andConditions +
               ", valueToApply=" + valueToApply +
               '}';
    }
Returns a copy of this rule without those conditions that can be resolved by the fetch vector.  Returns empty
if any of those conditions are false.
flags/src/main/java/com/yahoo/vespa/flags/json/Rule.java