public Choicepoint getChoicepoint(Condition condition, boolean create) {
        if (choicepoints == null) {
            if ( ! create) return null;
            choicepoints = new ArrayDeque<>();
        }
        Choicepoint choicepoint=lookupChoicepoint(condition);
        if (choicepoint == null) {
            if ( ! create) return null;
            choicepoint = new Choicepoint(this, condition);
            choicepoints.push(choicepoint);
        }
        return choicepoint;
    }
Add a choice point to this evaluation

@param  condition the creating condition
@param  create true to create this choicepoint if it is missing
@return the choicepoint, or null if not present, and create is false
container-search/src/main/java/com/yahoo/prelude/semantics/engine/RuleEvaluation.java