code: public String encode(String value) {
      if (value == null) { return null; }
      StringBuilder buffer = new StringBuilder();
      buffer.append(Prefix);
      buffer.append(charset);
      buffer.append(Sep);
      buffer.append(getEncoding());
      buffer.append(Sep);
      buffer.append(new String(Base64.encode(value.getBytes(charset))));
      buffer.append(Postfix);
      return buffer.toString();
    }
docs: Encodes a string into its Base64 form using the default charset. Unsafe characters are escaped.
  
  @param value string to convert to Base64 form
  @return Base64 string