fix response `content-type` is not set if access without access token

Kairlec

2023-05-15 ca103731c721aae3f5f622e58c679ed5c09fd9e9

 src/main/java/com/genersoft/iot/vmp/service/bean/MessageForPushChannel.java

@@ -48,6 +48,8 @@
     */
    private String mediaServerId;



    public static MessageForPushChannel getInstance(int type, String app, String stream, String gbId,
                                                    String platFormId, String platFormName, String serverId,
                                                    String mediaServerId){