Loopback 4 + MongoDB + openapi-to-graphql

Beforehand, hello to everyone!

I initialize Graphql in Loopback 4 like this:

  const graphqlPath = '/graphql';
  // @ts-ignore
  const oas: Oas3 = await (<Oas3>app.restServer.getApiSpec());
  console.log(graphqlHTTP);
  const {schema} = await createGraphQLSchema(oas, {
    strict: false,
    viewer: true,
    baseUrl: url,
  });
  //@ts-ignore
  const handler: graphqlHTTP.Middleware = graphqlHTTP({
    schema,
    graphiql: true,
  });
  app.mountExpressRouter(graphqlPath, handler);
  console.log(`Graphql: ${url}${graphqlPath}`);

Then I have a relation Favors>User (a User can have many Favors, but a Favor has only one User). I've created this relation with lb4 relation, and I haven't made any other change.

User Model:

  @hasMany(() => Favor)
  favors: Favor[];

Favor Model:

  @belongsTo(() => User)
  userId: string;

At the moment of the query (http://localhost:3000/graphql) this is what happens:

{
  favors {
    id
    userId
    user {
      id
    }
  }
}

I have no idea if it has something to do with the loopback-connector-mongodb which does not match ObjectId correctly, but I have no clue how to solve this.

My package.json:

    "@loopback/core": "^2.12.0",
    "openapi-to-graphql": "^2.2.5",
    "loopback-connector-mongodb": "^5.4.0",