@Override
    public RuleVO findById(final String id) {
        return RuleVO.buildRuleVO(ruleMapper.selectById(id),
                map(ruleConditionMapper.selectByQuery(new RuleConditionQuery(id)), RuleConditionVO::buildRuleConditionVO));
    }
find rule by id and namespaceId.

@param id primary key.
@return {@linkplain RuleVO}
shenyu-admin/src/main/java/org/apache/shenyu/admin/service/impl/RuleServiceImpl.java