code: @GET
      @Produces(MediaType.APPLICATION_JSON)
      @RequiresPermissions(I18nPermissions.KEY_READ)
      public Response getKeys(@QueryParam(PAGE_INDEX) @DefaultValue("0") long pageIndex,
              @QueryParam(PAGE_SIZE) @DefaultValue("10") int pageSize,
              @QueryParam(IS_MISSING) Boolean isMissing,
              @QueryParam(IS_APPROX) Boolean isApprox,
              @QueryParam(IS_OUTDATED) Boolean isOutdated,
              @QueryParam(SEARCH_NAME) String searchName) {
          WebAssertions.assertIf(pageSize > 0, "Page size should be greater than zero.");
          KeySearchCriteria keySearchCriteria = new KeySearchCriteria(isMissing, isApprox, isOutdated, searchName);
          Page page = new Page(pageIndex, pageSize);
          return Response.ok(keyFinder.findKeysWithTheirDefaultTranslation(page, keySearchCriteria)).build();
      }
docs: Returns a list of filtered keys without their translations.
  
  @param pageIndex  page index
  @param pageSize   page size
  @param isMissing  filter on missing default translation
  @param isApprox   filter on approximate default translation
  @param isOutdated filter on outdated key
  @param searchName filter on key name
  @return 200 - keys without translations