assertNull(dataStoreParams.getAsString("nonExistentKey"));
        assertEquals("defaultValue", dataStoreParams.getAsString("nonExistentKey", "defaultValue"));

        dataStoreParams.put("nullKey", null);
        assertEquals("defaultValue", dataStoreParams.getAsString("nullKey", "defaultValue"));
    }

    // Test getAsString with default value and non-String value

        assertNotNull(capturedCallback.get());
        assertNotNull(capturedParams.get());
        assertEquals("value1", capturedParams.get().getAsString("key1"));
        assertEquals("value2", capturedParams.get().getAsString("key2"));
    }

    public void test_store_withNullConfig() {
        // Test store with null config
        final AtomicBoolean storeCalled = new AtomicBoolean(false);

     * @return the parameter value as a String, or defaultValue if not found
     */
    public String getAsString(final String key, final String defaultValue) {
        final String value = getAsString(key);
        if (value != null) {
            return value;
        }
        return defaultValue;
    }

    /**

        final java.sql.Timestamp result = (java.sql.Timestamp) converter.getAsObject("2008/12/31 12:34:56");
        System.out.println(result);
        assertThat(converter.getAsString(result), is("2008/12/31 12:34:56"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testIsTarget() throws Exception {

        final java.sql.Date result = (java.sql.Date) converter.getAsObject("2008/01/16");
        System.out.println(result);
        assertThat(converter.getAsString(result), is("2008/01/16"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testIsTarget() throws Exception {

            defaultDataMap.put(fessConfig.getIndexFieldExpires(), documentExpires);
        }
        // segment
        defaultDataMap.put(fessConfig.getIndexFieldSegment(), initParamMap.getAsString(Constants.SESSION_ID));
        // created
        defaultDataMap.put(fessConfig.getIndexFieldCreated(), systemHelper.getCurrentTime());
        // boost

    }

    /**
     * @throws Exception
     */
    @Test
    public void testGetAsString() throws Exception {
        final NumberConverter converter = new NumberConverter("##0");
        assertThat(converter.getAsString(Integer.valueOf("100")), is("100"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testIsTarget() throws Exception {

 */
public interface Converter {

    /**
     * Returns the value as a string.
     *
     * @param value
     *            the value
     * @return the value as a string
     */
    String getAsString(Object value);

    /**
     * Returns the value as an object.
     *
     * @param value
     *            the value
     * @return the value as an object
     */
    Object getAsObject(String value);

        if (StringUtil.isEmpty(value)) {
            return null;
        }
        return DateConversionUtil.toSqlDate(value, pattern);
    }

    @Override
    public String getAsString(final Object value) {
        if (value == null) {
            return null;
        }
        return StringConversionUtil.toString((Date) value, pattern);
    }

    @Override

         * </ul>
         */
        private void deleteOldDocs() {
            if (Constants.FALSE.equals(initParamMap.getAsString(DELETE_OLD_DOCS))) {
                return;
            }
            final String sessionId = initParamMap.getAsString(Constants.SESSION_ID);
            if (StringUtil.isBlank(sessionId)) {
                logger.warn("Invalid sessionId at {}", dataConfig);