Those aren't needed since Tapestry-4.1.x provides all the functionality that they did.
However, tacos will soon re-include those in order to facilitate migration to the new version. Up to now,
Tree, AjaxForm and AjaxDirectLink have been ported (though without the
effects, preeffects and popup parameters).
There's no point in having such an encoder since a) there's no
AjaxDirectService anymore, its functionality has been included in Tapestry's
DirectService, b) the default DirectServiceEncoder does a good job packing
up the urls. So, if you're using it, then simply remove any references
(usually inside hivemind configuration files) to it.
