400 when trying to login as seller

[nik-pakhomov]

If you will make a request with sellers credentials via SDK library, you get 400 error. Code to reproduce:

        const string clientId = "your_client_id";
        const string userName = "user_name";
        const string password = "user_password";

        var ocClient = new OrderCloudClient(new OrderCloudClientConfig
        {
            ClientId = clientId,
            Roles = new []{ ApiRole.FullAccess },
            Username = userName,
            Password = password,
            GrantType = GrantType.Password
        });

        // Call any method via OrderCloud.SDK library cause 400 error on auth.
        var userInfo = await ocClient.Me.GetAsync();