code: public static String encodeToString(byte[] src) {
  		if (src == null) {
  			return null;
  		}
  		if (src.length == 0) {
  			return "";
  		}
  		String result;
  		try {
  			result = new String(delegate.encode(src), DEFAULT_CHARSET.displayName());
  		} catch (UnsupportedEncodingException e) {
  			// should not happen, UTF-8 is always supported
  			throw new IllegalStateException(e);
  		}
  		return result;
  	}
docs: Base64-encode the given byte array to a String.
  @param src the original byte array (may be {@code null})
  @return the encoded byte array as a UTF-8 String
  (or {@code null} if the input was {@code null})