code: public void setSessionAttribute(String key, Object newValue)
      {
          Object oldValue = sessionAttributes.put(key, newValue);
          propertyChangeSupport.firePropertyChange(key, oldValue, newValue);
          propertyChangeSupport.firePropertyChange(SESSION_ATTRIBUTES, null, sessionAttributes);
      }
docs: Add a key/value pair to the session attributes map.
  
  @param key
  a unique string code.
  @param newValue
  the associated value.