}
        return null;
    }

    /**
     * Gets the sort prefix used for identifying sort parameters in search queries.
     *
     * @return the sortPrefix
     */
    public String getSortPrefix() {
        return sortPrefix;
    }

    /**
     * Sets the sort prefix used for identifying sort parameters in search queries.
     *
     * @param sortPrefix the sortPrefix to set
     */

    @Test
    public void test_getSortPrefix() {
        assertEquals("sort:", queryHelper.getSortPrefix());
    }

    @Test
    public void test_setSortPrefix() {
        queryHelper.setSortPrefix("customSort:");
        assertEquals("customSort:", queryHelper.getSortPrefix());
    }

    @Test
    public void test_getAdditionalQuery() {