code: public static boolean isDataURL (@Nullable final String sURL)
    {
      if (sURL == null)
        return false;
      final String sRealURL = sURL.trim ();
      if (sRealURL.length () < PREFIX_DATA_URL.length ())
        return false;
      return sRealURL.substring (0, PREFIX_DATA_URL.length ()).toLowerCase (Locale.US).equals (PREFIX_DATA_URL);
    }
docs: Check if the passed URL is a data URL. It is checked, whether the passed
  URL starts with {@value #PREFIX_DATA_URL} (after trimming, case
  insensitive).
  
  @param sURL
  The URL to check. May be <code>null</code>.
  @return <code>true</code> if the passed URL is a data URL,
  <code>false</code> if not.