DartPluginRegistrant constructor Null safety

1. Flutter
2. dart:ui
3. DartPluginRegistrant
4. DartPluginRegistrant constructor

DartPluginRegistrant class

1. Constructors
2. DartPluginRegistrant
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==
11. Static methods
12. ensureInitialized