* This method adds a boost function that applies to all documents.
     *
     * @param scoreFunction the score function to add for boosting
     */
    public void addBoostFunction(final ScoreFunctionBuilder<?> scoreFunction) {
        boostFunctionList.add(new FilterFunctionBuilder(scoreFunction));
    }

    /**

        assertTrue(context.sortBuilders().get(0).toString().contains("_score"));
    }

    public void test_addBoostFunction_scoreFunction() {
        queryHelper.addBoostFunction(ScoreFunctionBuilders.weightFactorFunction(2.0f));

        QueryContext context = buildQuery("test");
        // Verify that function score query contains the added boost function