IdentityEquality<E> constructor Null safety

1. Flutter
2. collection
3. IdentityEquality<E>
4. IdentityEquality const constructor

IdentityEquality class

1. Constructors
2. IdentityEquality
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. equals
8. hash
9. isValidKey
10. noSuchMethod
11. toString
12. Operators
13. operator ==