MessageCodec<T> constructor Null safety

1. Flutter
2. services
3. MessageCodec<T>
4. MessageCodec constructor

MessageCodec class

1. Constructors
2. MessageCodec
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. decodeMessage
8. encodeMessage
9. noSuchMethod
10. toString
11. Operators
12. operator ==