Issue - Remove Message.getJSON().
Updated migration guide.
@@ -595,6 +595,12 @@ A number of deprecated APIs (since 4.0) have been removed.
[cols="1a,1a", options="header"]
|===
| CometD 4.0 | CometD 5.0
+
+| `Message.getJSON()`
+| No replacement. +
+ Use an implementation of `JSONContext.Client.generate(message)` on the client,
+ or an implementation of `JSONContextServer.generate(message)` on the server.
+
| `ClientSession.handshake(Map<String, Object>, **ClientSessionChannel**.MessageListener)`
| `ClientSession.handshake(Map<String, Object>, **ClientSession**.MessageListener)`
