ParameterDefinition constructor Null safety

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

ParameterDefinition class

1. Constructors
2. ParameterDefinition
3. Properties
4. hashCode
5. name
6. required
7. runtimeType
8. type
9. Methods
10. noSuchMethod
11. toString
12. Operators
13. operator ==