Not able to add nested list of object

[KartikGavhale]

i have a object say
class A{
int pro;
String description;
List bs;
C c;
}
class B{
String name;
int id;
}
class C{
int id;
String reference;
}

i was not able to make the floor db for these, i tried using the TypeConverters but still showing error as Column type is not supported for List and C are
Any suggestion wound be appreciated.