code: public String toMixedString() {
  		String result;
  		if(hasNoStringCache() || (result = getStringCache().mixedString) == null) {
  			getStringCache().mixedString = result = toNormalizedString(IPv6StringCache.mixedParams);
  		}
  		return result;
  	}
docs: This produces the mixed IPv6/IPv4 string.  It is the shortest such string (ie fully compressed).