ConsumerRunningInfo deserialize error

**BUG REPORT**

1. Please describe the issue you observed:

When no queues have been allocated, RocketMQ Broker get the client ConsumerRunningInfo will deserialize error.

```java
com.alibaba.fastjson.JSONException: syntax error, expect {, actual }
at com.alibaba.fastjson.parser.deserializer.MapDeserializer.parseMap(MapDeserializer.java:261)
at com.alibaba.fastjson.parser.deserializer.MapDeserializer.deserialze(MapDeserializer.java:71)
at com.alibaba.fastjson.parser.deserializer.MapDeserializer.deserialze(MapDeserializer.java:43)
at com.alibaba.fastjson.parser.deserializer.ContextObjectDeserializer.deserialze(ContextObjectDeserializer.java:9)
at com.alibaba.fastjson.parser.deserializer.FastjsonASMDeserializer_27_ConsumerRunningInfo.deserialze(Unknown Source)
at com.alibaba.fastjson.parser.deserializer.JavaBeanDeserializer.deserialze(JavaBeanDeserializer.java:287)
at com.alibaba.fastjson.parser.DefaultJSONParser.parseObject(DefaultJSONParser.java:705)
at com.alibaba.fastjson.JSON.parseObject(JSON.java:394)
at com.alibaba.fastjson.JSON.parseObject(JSON.java:298)
at com.alibaba.fastjson.JSON.parseObject(JSON.java:588)
at org.apache.rocketmq.remoting.protocol.RemotingSerializable.fromJson(RemotingSerializable.java:46)
at org.apache.rocketmq.remoting.protocol.RemotingSerializable.decode(RemotingSerializable.java:42)
```

Start with the ConsumerRunningInfo deserialization path, particularly RemotingSerializable.decode/fromJson and the MapDeserializer error shown in the report. Reproduce the broker response when no queues are allocated and verify that it can be deserialized without the reported syntax error.

Written by the indexing model from the issue text.