ComponentUtil.register(systemProperties, "systemProperties");

        pathMappingHelper = new PathMappingHelper() {
            @Override
            public void setPathMappingList(String sessionId,
                    List<org.codelibs.fess.opensearch.config.exentity.PathMapping> pathMappingList) {
                // Mock implementation
            }

            @Override

        pathMappingHelper.setPathMappingList(null, pathMappingList);
        assertNull(pathMappingHelper.getPathMappingList("test"));
    }

    @Test
    public void test_setPathMappingList_withNullList() {
        final String sessionId = "test";
        final List<PathMapping> pathMappingList = new ArrayList<PathMapping>();
        pathMappingHelper.setPathMappingList(sessionId, pathMappingList);

            final List<String> ptList = new ArrayList<>();
            ptList.add(Constants.PROCESS_TYPE_CRAWLING);
            ptList.add(Constants.PROCESS_TYPE_BOTH);
            pathMappingHelper.setPathMappingList(options.sessionId, pathMappingService.getPathMappingList(ptList));

            // duplicate host
            try {
                final DuplicateHostHelper duplicateHostHelper = ComponentUtil.getDuplicateHostHelper();