No such record error when having the generated stub file in a separate module

[dilanSachi]

Description:
Consider the following proto

syntax = "proto3";
import "google/protobuf/wrappers.proto";
service HelloWorld {
	rpc hello (google.protobuf.StringValue) returns (ABC);
}

message ABC {
	string s = 1;
}

Generate the stub file for this and add to a separate module and publish it.
Import this in a new grpc service and use as follows.

import ballerina/grpc;
import ballerina/io;
import dilan/stub_module;

@grpc:Descriptor {
    value: stub_module:SIMPLE_RPC_DESC
}
service "HelloWorld" on new grpc:Listener(9090) {
    remote function hello(string request) returns stub_module:ABC {
    	io:println(request);
        return {};
    }
}

When bal run is executed, following error can be seen.
A workaround is to add |error to the function return type. --> remote function hello(string request) returns stub_module:ABC|error {

error: No such record: ABC
        at ballerina.grpc.1:externRegister(service_endpoint.bal:137)
           ballerina.grpc.1.Listener:attach(service_endpoint.bal:66)

This is due to some native logic issues when building the service registry
https://github.com/ballerina-platform/module-ballerina-grpc/blob/master/native/src/main/java/io/ballerina/stdlib/grpc/ServiceResource.java#L59

[github-actions]

This issue is NOT closed with a proper Reason/ label. Make sure to add proper reason label before closing. Please add or leave a comment with the proper reason label now.

      - Reason/EngineeringMistake - The issue occurred due to a mistake made in the past.
      - Reason/Regression - The issue has introduced a regression.
      - Reason/MultipleComponentInteraction - Issue occured due to interactions in multiple components.
      - Reason/Complex - Issue occurred due to complex scenario.
      - Reason/Invalid - Issue is invalid.
      - Reason/Other - None of the above cases.