How to use whereMatchesKeyInQuery with class pointer

I call them tables, but in the code they are really just classes. I got the Users table (class that extends ParseUser) I got the TableAClass (class that extends ParseObject) and I got the TableBClass (class that extends ParseObject) B contains pointers to MyUserClass and TableAClass

ParseQuery<MyUserClass> query = ParseQuery.getQuery(MyUserClass.class);


ParseQuery<TableBClass> secondQuery = new ParseQuery<TableBClass>(
                    MyInstallsClass.class);

      

        
        
        
      

    

now the key part, I cannot request such

query.whereMatchesKeyInQuery( "objectId", "myuser_id",secondQuery);

      

        
        
        
      

    

because 'myuser_id' is not a string, it is a pointer to MyUserClass How do I get this query to work without adding additional String columns of type String that will contain the objectId