Callback triggered when a {@code Subject} logs-out of the system.
<p/>
This method will only be triggered when a Subject explicitly logs-out of the session. It will not
be triggered if their Session times out.
@param principals the identifying principals of the Subject logging out.
Callback triggered when a {@code Subject} logs-out of the system. <p/> This method will only be triggered when a Subject explicitly logs-out of the session. It will not be triggered if their Session times out.
@param principals the identifying principals of the Subject logging out.