fix bug

pcloud-service-book/src/main/java/com/pcloud/book/group/tools/SendWeixinRequestTools.java

@@ -336,8 +336,10 @@ public class SendWeixinRequestTools {
         }
         for (String nickName : names) {
             nickNames.remove(nickName);
+            if(StringUtils.isNotEmpty(nickName)) {
                 nameStr = nameStr + "@" + nickName + "  ";
             }
+        }
         JedisClusterUtils.setJson("BOOK:WEIXINGROUP:GUIDEUSER" + weixinGroupId,nickNames,600);
         return nameStr;
     }