Hello, @dez1337, when I debug the code as soon as it arrives in SteemJ steemJ = new SteemJ ();
Shoot the error below:

My Controller is like this:

UserData userData = new UserData();
        String username = "tiagoferezin";
        AccountName voter = new AccountName(username);
        userData = userDataRepositorio.retornaDadosDoUsuario(username);
        try {
            if ((userData.getIdUserData() == null)
                    || (userData.getIdUserData() == 0L)) {
                userData = new UserData();
                userData = UserDataFactory.gerarDadosUsuario(
                        userDataRepositorio, username);
            }
        } catch (Exception e) {
            // TODO: handle exception
            userData = new UserData();
            userData = UserDataFactory.gerarDadosUsuario(userDataRepositorio,
                    username);
        }

        Gson gson = new Gson();

        SteemJConfig myConfig = SteemJConfig.getInstance();
        myConfig.setResponseTimeout(0);
        myConfig.setDefaultAccount(voter);
        

        // Add and manage private keys:
        List<ImmutablePair<PrivateKeyType, String>> privateKeys = new ArrayList<>();
        privateKeys.add(new ImmutablePair<>(PrivateKeyType.POSTING, userData
                .getPostingKey()));
        privateKeys.add(new ImmutablePair<>(PrivateKeyType.ACTIVE, userData
                .getActiveKey()));
        //privateKeys.add(new ImmutablePair<>(PrivateKeyType.OWNER, userData.getOwnerKey()));
        //privateKeys.add(new ImmutablePair<>(PrivateKeyType.MEMO, userData.getMemoKey()));
        // ... add more keys if needed.

        myConfig.getPrivateKeyStorage().addAccount(
                myConfig.getDefaultAccount(), privateKeys);
        String tag = "pt";
    
            SteemJ steemJ = new SteemJ();

Please, how do I solve this problem, my friend?