FieldDefinition constructor Null safety

1. macro_builder
2. definition
3. FieldDefinition
4. FieldDefinition constructor

FieldDefinition class

1. Constructors
2. FieldDefinition
3. Properties
4. definingClass
5. hashCode
6. isAbstract
7. isExternal
8. name
9. runtimeType
10. type
11. Methods
12. noSuchMethod
13. toString
14. Operators
15. operator ==