RLocalCachedMap memory leak when using EvictionPolicy.WEAK
﻿### Expected behavior
Weak references should be cleared.

### Actual behavior
It seems that even when using static Strings for keys and values and only ```fastPut``` method the OOM error occurs after several thousands of invocations.
  
### Steps to reproduce or test case
I have created a separate repo to easier reproduce the problem:
https://github.com/pawelgrzes/redisson-mem-leak

### Redis version
4.0.9

### Redisson version
3.7.0

### Redisson configuration
```
RedissonClient redissonClient = Redisson.create();

LocalCachedMapOptions ops = LocalCachedMapOptions.defaults()
  .cacheSize(0)
  .timeToLive(0)
  .maxIdle(0)
  .reconnectionStrategy(LocalCachedMapOptions.ReconnectionStrategy.CLEAR)
  .syncStrategy(LocalCachedMapOptions.SyncStrategy.INVALIDATE)
  .evictionPolicy(LocalCachedMapOptions.EvictionPolicy.WEAK);

RLocalCachedMap<String, String> map = redissonClient.getLocalCachedMap("sample-cache", ops);
```

