isLoading property Null safety

1. farmershands
2. bar_graph
3. BarGraph
4. isLoading property

BarGraph class

1. Constructors
2. BarGraph
3. Properties
4. barItemsDay
5. cow
6. hashCode
7. hideGraph
8. isBiDirectional
9. isLoading
10. key
11. onScrollReachEnd
12. onScrollReachStart
13. onSelectAvgType
14. onSelectViewType
15. prevSelectedViewType
16. runtimeType
17. selectedAvgType
18. selectedViewType
19. size
20. Methods
21. createElement
22. createState
23. debugDescribeChildren
24. debugFillProperties
25. noSuchMethod
26. toDiagnosticsNode
27. toString
28. toStringDeep
29. toStringShallow
30. toStringShort
31. Operators
32. operator ==