*
     * If not present, the order will not be preserved.
     */
    @Internal
    public boolean isPreserveOrder() {
        return preserveOrder;
    }

    public void setPreserveOrder(boolean preserveOrder) {
        this.preserveOrder = preserveOrder;
    }

    @Internal
    public boolean getGroupByInstances() {
        return groupByInstances;
    }

    /**