The on destroy request event handler. Control classes should use this method to add any resource clean up code.
This method is guaranteed to be called before the Page object reference goes out of scope and is available for garbage collection.
{@link org.apache.click.control.Container} implementations should recursivelyinvoke the onDestroy method on each of their child controls ensuring that all controls receive this event.
Please note: a common problem when overriding onDestroy in subclasses is forgetting to call
super.onDestroy(). Consider carefully whether you should call
super.onDestroy() or not, especially for {@link org.apache.click.control.Container}s which by default call
onDestroy on all their child controls as well.