code: protected String getCachedDefaultLowerString() {
  		String result = cachedWildcardString;
  		if(result == null) {
  			synchronized(this) {
  				result = cachedWildcardString;
  				if(result == null) {
  					cachedWildcardString = result = getDefaultLowerString();
  				}
  			}
  		}
  		return result;
  	}
docs: this is like a shortcut to getDefaultString() when you already know !isMultiple() or you know isSinglePrefixBlock()