A representation of an InternalCacheEntry that does not have a reference to the key. This should be used if the key
is either not needed or available elsewhere as it is more efficient to marshall and unmarshall. Probably most useful
in cache stores.
Note that this should not be used to optimize memory overhead, since the saving of an additional reference to a key
(a single object reference) does not warrant the cost of constructing an InternalCacheValue, where an existing
InternalCacheEntry is already referenced.
Use of this interface only makes sense when marshalling is involved, since the cost of marshalling the key
again can be sidestepped using an InternalCacheValue if the key is already known/marshalled.