QOAuth1 creates an invalid signature for percent encoded query

#include <QtNetworkAuth>

void testOAuth() {
  QVariantMap oauthParams;
  oauthParams.insert("oauth_consumer_key", "consumerkey");
  oauthParams.insert("oauth_version", "1.0");
  oauthParams.insert("oauth_token", "token");
  oauthParams.insert("oauth_signature_method", "HMAC-SHA1");
  oauthParams.insert("oauth_nonce", "nonce");
  oauthParams.insert("oauth_timestamp", "time");

  QUrl url("http://example.com");
  QString key = "key";
  QString value = "@value";
  QOAuth1 auth;
  QList<QByteArray> results;
 
  {
    QUrlQuery query;
    query.addQueryItem(key, value);
    url.setQuery(query);
    results << auth.get(url)->url().toEncoded(); // http://example.com?key=@value
    QOAuth1Signature sig(url, QOAuth1Signature::HttpRequestMethod::Get, oauthParams);
    results << sig.hmacSha1().toBase64(); // SrVdwHkvs+tTuPls+i47bOD0H9Q=
  }

  {
    QUrlQuery query;
    query.addQueryItem(key, QUrl::toPercentEncoding(value));
    url.setQuery(query);
    results << auth.get(url)->url().toEncoded(); // http://example.com?key=%40value
    QOAuth1Signature sig(url, QOAuth1Signature::HttpRequestMethod::Get, oauthParams);
    results << sig.hmacSha1().toBase64(); // QHEARfCVhXa7L6Y1sirmOwkZRFE=
  }
}