code: public String toMixedString() {
  		String result;
  		if(hasNoStringCache() || (result = stringCache.mixedString) == null) {
  			if(hasZone()) {
  				stringCache.mixedString = result = toNormalizedString(IPv6StringCache.mixedParams);
  			} else {
  				result = getSection().toMixedString();//the cache is shared so no need to update it here
  			}
  		}
  		return result;
  	}
docs: Produces a string in which the lower 4 bytes are expressed as an IPv4 address and the remaining upper bytes are expressed in IPv6 format.
  
  This the mixed IPv6/IPv4 format described in RFC 1884 https://tools.ietf.org/html/rfc1884
  
  @return