code: private void releaseAndOfferIfHealthy(Channel channel, Promise<Void> promise, Future<Boolean> future)
              throws Exception {
          if (future.getNow()) { //channel turns out to be healthy, offering and releasing it.
              releaseAndOffer(channel, promise);
          } else { //channel not healthy, just releasing it.
              handler.channelReleased(channel);
              promise.setSuccess(null);
          }
      }
docs: Adds the channel back to the pool only if the channel is healthy.
  @param channel the channel to put back to the pool
  @param promise offer operation promise.
  @param future the future that contains information fif channel is healthy or not.
  @throws Exception in case when failed to notify handler about release operation.