In the related JIRA issue for Jetspeed,
JS2-1013, I've provided a little bit background why Pluto container no longer needs the PortletEntity:
With the major rewrite of the Pluto 2.0.0 container, the need and usage of the PortletEntity no longer is needed within Pluto itself, nor in Jetspeed.
The Portlet specification (2.0) describes the concept of a PortletEntity as follows in PLT.5.3.1:
"At runtime, when serving requests, one or more preference objects are associated with a portlet.
The resulting association of a specific preference object with a portlet is called the portlet entity.
This concept is abstract. There is not a concrete object that represents the portlet entity.
The portal / portlet container merely associates the proper preference object with the context that is passed to the executing portlet."
As the Pluto container does not impose in any way how the proper preference object is associated, but delegates this to the portal (like Jetspeed) for which it provides the current PortletWindow as selector,
it is completely up to the embedding portal how to select the proper preference object. Within the Pluto container, there is no concrete usage anymore of a PortletEntity nor wat it should be or do, if it even exists.