Stores a user ID and password in the credential vault slot with the given ID.
This function produces an error if the slot does not contain secrets that are userid or password types; or if the secret cannot be stored.
portalLib.setCredential(
slotId STRING in,
userId STRING in,
password STRING in)
slotid String = portalLib.getPreferenceValue("userSlot", null);
userid String = "portalUser";
password String = "userPasswd";
portalLib.setCredential(slotid, userid, password);