Provides classes and interface for RMI distributed garbage-collection (DGC).

  Provides classes and interface for RMI distributed
garbage-collection (DGC). When the RMI server returns an object to
its client (caller of the remote method), it tracks the remote
object's usage in the client. When there are no more references to the
remote object on the client, or if the reference's ``lease'' expires and
not renewed, the server garbage-collects the remote object.