PluginManager constructor Null safety

1. baguette
2. PluginManager
3. PluginManager
4. PluginManager factory constructor

PluginManager class

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