@Override
    public Object saveState(FacesContext context) {
        // reset component for MyFaces view pooling
        if (customEvents != null) {
            customEvents.clear();
        }

        return super.saveState(context);
    }
Prohibits client-side manipulation of disabled entries, when CSS style-class ui-state-disabled is removed.

@param facesContext The current FacesContext.
@param label The label to be used in the error message.
@param newEntries new/set entries of model source/target list
@param oldEntries old/former entries of model source/target list
@see <a href="https://github.com/primefaces/primefaces/issues/2127">GitHub #2127</a>
primefaces/src/main/java/org/primefaces/component/picklist/PickList.java