Fix deserialization with custom addition

- try-catch based approach on Subtype annotation mentions
- Also pass custom list of candidates

Author: rpanackal

orchestration/src/main/java/com/sap/ai/sdk/orchestration/OrchestrationChatResponse.java

@@ -73,8 +73,7 @@ public List<Message> getAllMessages() throws UnsupportedOperationException{
         throw new UnsupportedOperationException("Currently MultiChatMessage type not supported by convenience API");
       }
     }
-    // TODO: Review { bypassing throwing OrchestrationClientException and
-    //       assumes AssistantMessage is always only type ChatMessage }
+
     messages.add(new AssistantMessage(getChoice().getMessage().getContent()));
     return messages;
   }