dubbo 3.0.0 use triple protocol , How to generate dubbo service use protocol idl and gradle

### Environment

* Dubbo version: 3.0.0
* protocol: triple
* Operating System version: macos
* Java version: 8

### Steps to reproduce this issue

1. hello.proto
```proto
syntax = "proto3";

package com.earthchen.rpc.lib;

option java_multiple_files = true;
option java_package = "com.earthchen.rpc.lib";
option java_outer_classname = "HelloWorldProto";

// The greeting service definition.
//service MyService {
// // Sends a greeting
// rpc SayHello (HelloRequest) returns (HelloReply) {
// }
//
//}

// The request message containing the user's name.
message HelloRequest {
string name = 1;
}

// The response message containing the greetings
message HelloReply {
string message = 1;
}
```