XXX: Cache implementation currently not complete.
The ConnectionContext should start building a CacheKey
as soon as it sees a window with expiration-cache != 0.
It should do this in the action stage, because each window is
seen in the action stage.
A Map that wraps another map and uses different keys in the wrapped
map than the keys that are exposed.
The constructor is passed the map to be wrapped, and a keyLinkMap
that maps keys as they are used by users of the map to different keys that
are really used in the wrapped map.
A PortletConnection is used to obtain
Action and
Render objects.
For implementations that support only one portlet for each connection,
the pattern of use is:
A servlet that uses a class implementing javax.portlet.Portlet.
This servlet supports the following configuration items.
Items marked with a * can be set as init-param.