First calls <code>super.onLogout(principals)</code> to ensure a logout notification is issued, and for each
wrapped {@code Realm} that implements the {@link LogoutAware LogoutAware} interface, calls
<code>((LogoutAware)realm).onLogout(principals)</code> to allow each realm the opportunity to perform
logout/cleanup operations during an user-logout.
<p/>
Shiro's Realm implementations all implement the {@code LogoutAware} interface by default and can be
overridden for realm-specific logout logic.
@param principals the application-specific Subject/user identifier.
First calls <code>super.onLogout(principals)</code> to ensure a logout notification is issued, and for each wrapped {@code Realm} that implements the {@link LogoutAware LogoutAware} interface, calls <code>((LogoutAware)realm).onLogout(principals)</code> to allow each realm the opportunity to perform logout/cleanup operations during an user-logout. <p/> Shiro's Realm implementations all implement the {@code LogoutAware} interface by default and can be overridden for realm-specific logout logic.
@param principals the application-specific Subject/user identifier.