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

Kairlec

2023-05-15 ca103731c721aae3f5f622e58c679ed5c09fd9e9

 src/main/java/com/genersoft/iot/vmp/gb28181/bean/WvpSipDate.java

@@ -10,6 +10,11 @@
 */
public class WvpSipDate extends SIPDate {

    /**
     *
     */
    private static final long serialVersionUID = 1L;
    
    private Calendar javaCal;

    public WvpSipDate(long timeMillis) {