The Assign Credentials agent is available only in a per-request policy (not in a subroutine).
If the password is shared, the agent gets user credentials from the main session, takes the
username and password source session variable names. and stores them in perflow variables. The
Assign Credentials agent must precede the subroutine where the credential needs to be reused. The
logon page is shown only when perflow credentials variables are empty.