update view_submission properties

Author: vegeris

slack-app-backend/src/main/java/com/slack/api/app_backend/views/payload/ViewSubmissionPayload.java

@@ -93,4 +93,16 @@ public static class Interactor {
         private String secret;
     }
 
+    private String entityUrl;
+    private ExternalRef externalRef;
+    private String appUnfurlUrl;
+    private String messageTs;
+    private String channel;
+
+    @Data
+    public static class ExternalRef {
+        private String id;
+        private String type;
+    }
+
 }