ICommand<T extends IContext> constructor Null safety

1. nyxx_commands
2. nyxx_commands
3. ICommand<T extends IContext>
4. ICommand constructor

ICommand class

1. Constructors
2. ICommand
3. Properties
4. checks
5. execute
6. hashCode
7. localizedNames
8. name
9. onPostCall
10. onPreCall
11. options
12. parent
13. resolvedOptions
14. runtimeType
15. Methods
16. check
17. invoke
18. noSuchMethod
19. toString
20. Operators
21. operator ==