code: @Override
      public synchronized void invalidate(String key, boolean fullExpire) {
          Entry entry = get(key);
          if (entry != null) {
              entry.softTtl = 0;
              if (fullExpire) {
                  entry.ttl = 0;
              }
              put(key, entry);
          }
  
      }
docs: Invalidates an entry in the cache.
  @param key Cache key
  @param fullExpire True to fully expire the entry, false to soft expire