ManagedBacking constructor Null safety

1. conduit_core
2. conduit
3. ManagedBacking
4. ManagedBacking constructor

ManagedBacking class

1. Constructors
2. ManagedBacking
3. Properties
4. contents
5. hashCode
6. runtimeType
7. Methods
8. noSuchMethod
9. removeProperty
10. setValueForProperty
11. toString
12. valueForProperty
13. Operators
14. operator ==