code: @Override
  	public String getBundleDataHashCode(String variantKey) {
  		if (StringUtils.isEmpty(variantKey)) {
  			return this.urlPrefix;
  		} else {
  			return (String) prefixMap.get(variantKey);
  		}
  	}
docs: /*
  (non-Javadoc)
  
  @see
  net.jawr.web.resource.bundle.JoinableResourceBundle#getBundleDataHashCode
  ()