docs: public String getHostName() {
          String host = requestHeaders.getFirst(Headers.HOST);
          if (host == null) {
              host = getDestinationAddress().getHostString();
          } else {
              if (host.startsWith("[")) {
                  host = host.substring(1, host.indexOf(']'));
              } else if (host.indexOf(':') != -1) {
                  host = host.substring(0, host.indexOf(':'));
              }
          }
          return host;
      }