}

    /**
     * Sets the default operator to use between query terms.
     *
     * @param defaultOperator the default operator (AND or OR)
     */
    public void setDefaultOperator(final Operator defaultOperator) {
        this.defaultOperator = defaultOperator;
    }

    /**
     * Adds a filter to the query processing chain.
     * The filter chain is recreated after adding the filter.