code: public static String addDomainIfMissing(final String aUrl, final String aDomain) {
      if (aUrl != null && !aUrl.isEmpty() && aUrl.startsWith("/")) {
        return aDomain + aUrl;
      }
  
      return aUrl;
    }
docs: adds the domain if missing.
  
  @param aUrl the url to check
  @param aDomain the domain to add
  @return the url including the domain