code: public static boolean isValid (@Nullable final String sURL)
    {
      if (StringHelper.hasNoText (sURL))
        return false;
  
      final String sUnifiedURL = getUnifiedURL (sURL);
      return PATTERN.matcher (sUnifiedURL).matches ();
    }
docs: Checks if a value is a valid URL.
  
  @param sURL
  The value validation is being performed on. A <code>null</code> or
  empty value is considered invalid.
  @return <code>true</code> if URL is valid, <code>false</code> otherwise.