RealmList is used to model one-to-many relationships in a RealmObject.
A RealmList has two modes:
managed mode all objects are persisted inside a Realm whereas in
unmanaged mode it works as a normal MutableList.
Only Realm can create managed RealmLists. Managed RealmLists will automatically update their content whenever the underlying Realm is updated. Said content can only be accessed using the getter of a RealmObject.
Unmanaged RealmLists can be created by the user and can contain both managed and unmanaged RealmObjects. This is useful when dealing with JSON deserializers like Gson or other frameworks that inject values into a class. Unmanaged elements in a list can be added to a Realm using the MutableRealm.copyToRealm method.