UnmodifiableMapView class

1. Constructors
2. UnmodifiableMapView
3. Properties
4. entries
5. hashCode
6. isEmpty
7. isNotEmpty
8. keys
9. length
10. runtimeType
11. values
12. Methods
13. addAll
14. addEntries
15. cast
16. clear
17. containsKey
18. containsValue
19. forEach
20. map
21. noSuchMethod
22. putIfAbsent
23. remove
24. removeWhere
25. retype
26. toString
27. update
28. updateAll
29. Operators
30. operator ==
31. operator []
32. operator []=