RealmDictionary is a specialization for RealmMaps whose keys are
Similarly to RealmList or RealmSet,
RealmMap can operate in managed and unmanaged modes. In managed mode a
RealmDictionary persists all its contents in a Realm instance whereas unmanaged dictionaries are backed by an in-memory LinkedHashMap.
A managed dictionary can only be created by Realm and will automatically update its content whenever its underlying realm is updated. Managed dictionaries can only be accessed using the getter that points to a
RealmDictionary property of a managed RealmObject.
Unmanaged dictionaries can be created by calling realmDictionaryOf and may contain both managed and unmanaged RealmObjects. Unmanaged dictionaries can be added to a realm using the MutableRealm.copyToRealm function with an object containing an unmanaged dictionary.
the type of the values stored in this map