docs: public static String getSignatureBaseString(String nonce, String requestMethod, String headerHost, String requestUrl,
        @Nullable String payloadBodyHash, @Nullable String ext) throws AuthException {
      return nonce + '\n'
          + requestMethod.toUpperCase() + '\n'
          + normalizeUrl(headerHost, requestUrl) + '\n'
          + (payloadBodyHash != null ? payloadBodyHash : "") + '\n'
          + (ext != null ? ext : "") + '\n';
    }