docs: private String createAuthEncoded() {
          JsonObject ret = new JsonObject();
          putNonNull(ret, "username", username);
          putNonNull(ret, "password", password);
          putNonNull(ret, "email", email);
          putNonNull(ret, "auth", auth);
          try {
              return encodeBase64ChunkedURLSafeString(ret.toString().getBytes("UTF-8"));
          } catch (UnsupportedEncodingException e) {
              return encodeBase64ChunkedURLSafeString(ret.toString().getBytes());
          }
      }