cleanPlugins method Null safety

1. baguette
2. Plugin
3. Plugin
4. cleanPlugins method

Plugin class

1. Constructors
2. Plugin
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. addPlugin
8. cleanPlugins
9. getPlugin
10. noSuchMethod
11. removePlugin
12. toString
13. Operators
14. operator ==