SyncModel constructor Null safety

1. irte_engine
2. sync_model
3. SyncModel
4. SyncModel constructor

SyncModel class

1. Constructors
2. SyncModel
3. Properties
4. hashCode
5. isNewRecord
6. primaryKey
7. runtimeType
8. Methods
9. afterSave
10. beforeSave
11. noSuchMethod
12. toString
13. Operators
14. operator ==