How enable prompting username and password in RDP

[Amin Radjabov]

 
Hello, I have update the guacamole and guacd to version 1.3.0
I try to add an RDP server and leave empty username, password, domain and set 
NLA auth in connection settings. but I have not been prompted to enter these 
while I am logged into the RDP connection.
Connections only work when I am filling up these fields in settings. What do I 
need to fill in on settings for not storing username/password in the database?