public interface DemoApi {

    String methodA();

    String testCallbackMethod(String name,  ApiCallback callback);
    
    interface ApiCallback {
        String callbackMethod();
    }
}

@DubboService(methods = @Method(name="testCallbackMethod", 
                arguments = {@Argument(index = 1, type = "DemoApi$ApiCallback", callback = true)}))
public class DemoProvider implements DemoApi {
   
    @Override
    public String methodA() {
        return "ok";
    }
  
  @Override
    public String testCallbackMethod(String name, ApiCallback callback) {
        String s = callback.callbackMethod();
        return "ok";
    }
}

@RestController
public class TestController{

    @DubboReference
    DemoApi demo;

    private DemoApi.ApiCallback callback = new DemoApi.ApiCallback() {
        @Override
        public String callbackMethod() {
            //rpc context has been lost
            System.out.println("callback:" + RpcContext.getContext().getAttachment("test"));
            //This is just a simple simulation problem, in fact, it may call other services
            return demo.methodA();
        }
    };

    @GetMapping("/testDubboCallback")
    public ResponseEntity<String> testDubboCallback() {
        RpcContext.getContext().setAttachment("test", "abc");
        return ResponseEntity.ok(demo.testCallbackMethod("param" ,callback));
    }

}