docs: @Override
      public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) throws Exception {
          if (!notifiedOnFailure) {
              notifiedOnFailure = true;
              try {
                  responseHandler.onFailure(new SdkClientException("Unable to execute HTTP request.", cause));
              } finally {
                  ctx.channel().close();
              }
          }
      }