can't accumulate category job slight an interface general list argument

just got doubt generics, since doesn't accumulate controlling general list? the possible, anyway around it? many conclude any answer.

// interface used serviceasync inteface.
public interface baseobject
{
    open twine getid();
}

// category implements interface
public category _modeldto implements baseobject, isserializable
{
    stable twine id;

    open vacant setid(string id)
    {
        this.id = id;
    }

    open twine getid()
    {
        relapse id;
    }
}

// interface used serviceasync inteface.
public interface myasync<t>
{
     // zero here.
}

// use interface both interfaces above.
public interface serviceasync
{
    open vacant getlist(myasync<list<? extends baseobject>> callback);
}

public category myclass
{
    serviceasync use = (some implementation);
    myasync<list<_modeldto>> callback = new myasync<list<_modeldto>>()
    {

    };

    service.getlist(callback);  // does compile, says arguments applicable????
}