Provides a view of this map as having RK keys and RV instances, if necessary.
If this map is already a Map<RK, RV>, it is returned unchanged.
If this set contains only keys of type RK and values of type RV, all read operations will work correctly. If any operation exposes a non-RK key or non-RV value, the operation will throw instead.
Entries added to the map must be valid for both a Map<K, V> and a Map<RK, RV>.
Map<RK, RV> cast<RK, RV>() =>
UnmodifiableMapView<RK, RV>(_map.cast<RK, RV>());
© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dart.dev/stable/2.5.0/dart-collection/UnmodifiableMapView/cast.html