RFC 2732 has amended RFC 2396 with regard to the definition of host. RFC 2373 section 3 document these changes:
   The following changes to the syntax in RFC 2396 are made:
   (1) change the 'host' non-terminal to add an IPv6 option:

      host = hostname | IPv4address | IPv6reference
      ipv6reference = "[" IPv6address "]"

   where IPv6address is defined as in RFC2373 [ARCH].

However, right now URI and URL getHost() method implementation doesn't comform to this.