Mapping data of parent JSF dialog get data back from Child Component

Hi, I have a scenario like this: I build an Ivy component for user selection(Autocomplete). Then after select a user, parent dialog should receive the selected IUser object.

My current solution :

Parent dialog : Dataclass UserData Child Component Mapping data in startLink

With this solution, I can get the selected IUser via object userData. Because I think in this case, 2 variables point to the same memory, so parent dialog can get the updated data when it change on child component.

But I have a requirement to make it more flexible, do not use object userData. User UserName or IUser for input parameter.Like this Parent dialog :

But when I try to mapping like my current solution. Parent dialog can not get the selected data from child component. I think because UserName is a string, and it will create a new object when we change it. For IUser, it's an Interface.

So if anybody has experience to solve it. Please help me.

Thank you and regards.