HashMap <String, Negotiator> cachedMap = getCache();
 if (cachedMap != null) {
     negotiator = cachedMap.get(getHost());
     if (negotiator != null) {
         cachedMap.remove(getHost()); // so that it is only used once
     }
 }

Instead of separate HashMap.get+remove call, we can use single HashMap.remove call and use its return value.
It makes code a bit cleaner and faster.