1. @override
Future storeToken(AuthServer server, AuthToken t, { AuthCode issuedFrom })

Asks this instance to store a AuthToken for server.

This method must persist the token t. If issuedFrom is not null, it must associate the issuedFrom AuthCode with t in storage, such that t can be found again by issuedFrom's AuthCode.code, even if t has been refreshed later.

Source 

@override
Future storeToken(AuthServer server, AuthToken t,
    {AuthCode issuedFrom}) async {
  var storage = new ManagedToken.fromToken(t);
  var query = new Query<ManagedToken>(context)..values = storage;

  if (issuedFrom != null) {
    query.where.code = whereEqualTo(issuedFrom.code);
    query.values.code = issuedFrom.code;
    var outToken = await query.updateOne();
    if (outToken == null) {
      throw new AuthServerException(AuthRequestError.invalidGrant,
          new AuthClient(t.clientID, null, null));
    }
  } else {
    await query.insert();
  }

  return pruneTokens(t.resourceOwnerIdentifier);
}