The hash calculation error causes the label of metrics not to be updated.

[cserwen]

Describe the bug
When the consumer is closed, the countOfOnlineConsumers of metrhc: rocketmq_group_diff won't be changed to 0.

To Reproduce
Steps to reproduce the behavior:

1. Start a consumer and running for a while.
2. Shutdown it and you will see the value of countOfOnlineConsumers still is 1.

Expected behavior
The value of countOfOnlineConsumers should be 0.

Screenshots

Additional context
The root cause is that the following code.

rocketmq-exporter/src/main/java/org/apache/rocketmq/exporter/model/metrics/ConsumerTopicDiffMetric.java

Line 65 in 85cf905

public boolean equals(Object obj) {

The class ConsumerTopicDiffMetric has four fields:

private String group;
private String topic;
private String countOfOnlineConsumers;
private String msgModel; //0:broadcast, 1:cluster

It only calculates topic abd group. So when countOfOnlineConsumers changed, The new key will not be added.