in web/src/main/java/org/apache/commons/chain2/web/servlet/ServletSessionScopeMap.java [124:139]
public Object put(String key, Object value) {
if (value == null) {
return remove(key);
}
// Ensure the Session is created, if it
// doesn't exist
if (session == null) {
session = request.getSession();
request = null;
}
Object previous = session.getAttribute(key);
session.setAttribute(key, value);
return previous;
}