Fix: export method getArgsTypeList for extension (#1911)

diff --git a/protocol/dubbo/impl/hessian.go b/protocol/dubbo/impl/hessian.go
index 79e531a..c235843 100644
--- a/protocol/dubbo/impl/hessian.go
+++ b/protocol/dubbo/impl/hessian.go
@@ -129,7 +129,7 @@
 		logger.Infof("request args are: %+v", request.Params)
 		return nil, perrors.Errorf("@params is not of type: []interface{}")
 	}
-	types, err := getArgsTypeList(args)
+	types, err := GetArgsTypeList(args)
 	if err != nil {
 		return nil, perrors.Wrapf(err, " PackRequest(args:%+v)", args)
 	}
@@ -392,7 +392,7 @@
 	}
 }
 
-func getArgsTypeList(args []interface{}) (string, error) {
+func GetArgsTypeList(args []interface{}) (string, error) {
 	var (
 		typ   string
 		types string