@Override
    public StringBuilder toString(StringBuilder string, SerializationContext context, Deque<String> path, CompositeNode parent) {
        string.append("if (");
        getCondition().toString(string, context, path, this).append(", ");
        getTrueExpression().toString(string, context, path, this).append(", ");
        getFalseExpression().toString(string, context, path, this);
        if (trueProbability != null) {
            string.append(", ").append(trueProbability);
        }
        return string.append(')');
    }
The average probability that the condition of this node will evaluate to true, or null if not known
searchlib/src/main/java/com/yahoo/searchlib/rankingexpression/rule/IfNode.java