code: static void encUserInfo(final StringBuilder sb, final String content, final Charset charset) {
          urlEncode(sb, content, charset, USERINFO, false);
      }
docs: Encode a String using the {@link #USERINFO} set of characters.
  <p>
  Used by URIBuilder to encode the userinfo segment.
  @param content
  the string to encode, does not convert space to '+'
  @param charset
  the charset to use
  
  @return the encoded string