/**
   * Split a freeform string into a host and port, without strict validation.
   *
   * <p>Note that the host-only formats will leave the port field undefined. You can use {@link
   * #withDefaultPort(int)} to patch in a default value.
   *
   * @param hostPortString the input string to parse.
   * @return if parsing was successful, a populated HostAndPort object.