code: public void addFuture(ListenableFuture<Boolean, OperationCompletionListener> future) {
          future.addListener(this);
          if (future.isDone()) countDown();
          this.futures.add(future);
      }
docs: /*
  (non-Javadoc)
  
  @see
  com.netflix.evcache.operation.EVCacheLatchI#addFuture(net.spy.memcached.internal.ListenableFuture)