                 json["title"] = title
                 json["subtitle"] = subtitle
                 json["attachmentUrl"] = attachmentUrl
+                json["apnsCollapseId"] = apnsCollapseId
                 
                 if !json.isEmpty {
                     return json

            let title: String?
            let subtitle: String?
            let attachmentUrl: String?
            
            /**
             The required intializer for the `Apns` class.

                self.title = title
                self.subtitle = subtitle
                self.attachmentUrl = attachmentUrl
                self.apnsCollapseId = apnsCollapseId
            }
            
            internal var jsonFormat: [String: Any]? {
