修复 设备注册时报错 #799

src/main/java/com/genersoft/iot/vmp/gb28181/auth/DigestServerAuthenticationHelper.java

@@ -171,7 +171,7 @@ public class DigestServerAuthenticationHelper  {
      */
     public boolean doAuthenticatePlainTextPassword(Request request, String pass) {
         AuthorizationHeader authHeader = (AuthorizationHeader) request.getHeader(AuthorizationHeader.NAME);
-        if ( authHeader == null ) {
+        if ( authHeader == null || authHeader.getRealm() == null) {
             return false;
         }
         String realm = authHeader.getRealm().trim();