docs: void closeCurrentConnections() {
          final CountDownLatch latch = new CountDownLatch(hostThreadData.size());
          for(final Map.Entry<XnioIoThread, HostThreadData> data : hostThreadData.entrySet()) {
              data.getKey().execute(new Runnable() {
                  @Override
                  public void run() {
                      ConnectionHolder d = data.getValue().availableConnections.poll();
                      while (d != null) {
                          IoUtils.safeClose(d.clientConnection);
                          d = data.getValue().availableConnections.poll();
                      }
                      data.getValue().connections = 0;
                      latch.countDown();
                  }
              });
          }
          try {
              latch.await(10, TimeUnit.SECONDS);
          } catch (InterruptedException e) {
              throw new RuntimeException(e);
          }
      }