default PageInfo<R> searchByPage(final PageCondition<Q> pageCondition) {
        doConditionPreProcessing(pageCondition.getCondition());
        PageHelper.startPage(pageCondition.getPageNum(), pageCondition.getPageSize());
        return new PageInfo<>(searchByCondition(pageCondition.getCondition()));
    }
search by page condition.

@param pageCondition page condition
@return list
shenyu-admin/src/main/java/org/apache/shenyu/admin/service/PageService.java