code: public static String unicodeEscaped(final char ch) {
          return "\\u" +
                  HEX_DIGITS[(ch >> 12) & 15] +
                  HEX_DIGITS[(ch >> 8) & 15] +
                  HEX_DIGITS[(ch >> 4) & 15] +
                  HEX_DIGITS[(ch) & 15];
      }
docs: <p>Converts the string to the Unicode format '\u0020'.</p>
  
  <p>This format is the Java source code format.</p>
  
  <pre>
  CharUtils.unicodeEscaped(' ') = "\u0020"
  CharUtils.unicodeEscaped('A') = "\u0041"
  </pre>
  
  @param ch  the character to convert
  @return the escaped Unicode string