DefinitionMacro constructor Null safety

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

DefinitionMacro class

1. Constructors
2. DefinitionMacro
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. noSuchMethod
8. toString
9. Operators
10. operator ==