- [ ] I have searched the [issues](https://github.com/apache/dubbo/issues) of this repository and believe that this is not a duplicate.
- [ ] I have checked the [FAQ](https://github.com/apache/dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: xxx
* Operating System version: xxx
* Java version: xxx

### Steps to reproduce this issue

![image](https://user-images.githubusercontent.com/8758457/59562427-2e06c800-905f-11e9-9bff-9ea54d87fc6d.png)
![image](https://user-images.githubusercontent.com/8758457/59562435-51317780-905f-11e9-930b-a66bc866ccf1.png)


Pls. provide [GitHub address] to reproduce this issue.

### Expected Result

What do you expected from the above steps？

### Actual Result

What actually happens?

If there is an exception, please attach the exception trace:

```
Just put your stack trace here!
```

expireThread.setExpirationInterval(expirationInterval);
    }
    @Override
    public V put(K key, V value) {
        ExpiryObject answer = delegateMap.put(key, new ExpiryObject(key, value, System.currentTimeMillis()));
        if (answer == null) {
            return null;
        }
        return answer.getValue();
    }
    @Override
    public V get(Object key) {
        ExpiryObject object = delegateMap.get(key);
        if (object != null) {
            object.setLastAccessTime(System.currentTimeMillis());
            return object.getValue();
        }
        return null;
    }
    @Override
    public V remove(Object key) {
        ExpiryObject answer = delegateMap.remove(key);
        if (answer == null) {
            return null;
        }
        return answer.getValue();
    }
    @Override
    public boolean containsKey(Object key) {
        return delegateMap.containsKey(key);