JSF / Xpages how to clear sessionscopes?

I want to clear the current sessionscopes in my xpages application and reload them again. I have tried:

public Map<String, Object> sesScope;
this.sesScope = JSFUtil.getSessionScope();

clearMap(sesScope);

private void clearMap(Map<String, Object> map ){ // Get iterator for the keys
    String methodName = new Object(){}.getClass().getEnclosingMethod().getName();
    utils.printToConsole(this.getClass().getSimpleName().toString() + " " + methodName);
    utils.printToConsole("-------before removing------");
    utils.printToConsole(map.toString());

    Set keyset = map.keySet();
    Iterator itr = keyset.iterator();
    while (itr.hasNext()) {
        itr.next();
        itr.remove();
    }

    utils.printToConsole("--------After removing-------");
    utils.printToConsole(map.toString());
}

Somehow I can not simply say sesScope.clear() since that would result in an error:

java.lang.UnsupportedOperationException at com.sun.faces.context.BaseContextMap.clear(ExternalContextImpl.java:392)

How do I clear the sessionscope properly?

I do this to clear sessionScope:

for (final String key : JSFUtil.getSessionScope().keySet()) {
    JSFUtil.getSessionScope().remove(key);
}