develop分支的服务测试不支持triple接口？

- [ ] I have searched the [issues](https://github.com/apache/dubbo-admin/issues) of this repository and believe that this is not a duplicate.
- [ ] I have checked the [REAMDE](https://github.com/apache/dubbo-admin/blob/develop/README.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo Admin version: branch develop, 0.5.0-SNAPSHOT
* Registry center detail (type and version): zookeeper, org.apache.curator.test.TestingServer, curator-test-5.3.0
* Operating System version: win7
* Java version: 1.8

### Steps to reproduce this issue

1. 本地依次启动TestingServer, triple provider, org.apache.dubbo.admin.DubboAdminApplication
2. 在服务查询中选择一个unary接口，点击测试
3. provider收到请求，但body为空。triple consumer可正常访问provider接口

Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?
provider收到请求，但请求pb对象的数据为空（无法序列化？）

If there is an exception, please attach the exception trace:
provider无报错

Reproduce the issue by starting TestingServer, a triple provider, and org.apache.dubbo.admin.DubboAdminApplication, then test a unary interface from service search. Inspect the request path used by the service test and compare it with a working triple consumer. Done means the provider receives the serialized protobuf request data rather than an empty body.

Written by the indexing model from the issue text.