checkArgument(
          !portString.startsWith("+") && CharMatcher.ascii().matchesAllOf(portString),
          "Unparseable port number: %s",
          hostPortString);
      try {
        port = Integer.parseInt(portString);
      } catch (NumberFormatException e) {
        throw new IllegalArgumentException("Unparseable port number: " + hostPortString);
      }