code: public static HostAndPort fromHost(String host) {
      HostAndPort parsedHost = fromString(host);
      checkArgument(!parsedHost.hasPort(), "Host has a port: %s", host);
      return parsedHost;
    }
docs: Build a HostAndPort instance from a host only.
  
  <p>Note: Non-bracketed IPv6 literals are allowed. Use {@link #requireBracketsForIPv6()} to
  prohibit these.
  
  @param host the host-only string to parse. Must not contain a port number.
  @return if parsing was successful, a populated HostAndPort object.
  @throws IllegalArgumentException if {@code host} contains a port number.
  @since 17.0