code: protected synchronized void unmapSubscrip (int oid)
      {
          ClientProxy rec;
          synchronized (_subscrips) {
              rec = _subscrips.remove(oid);
          }
          if (rec != null) {
              rec.unsubscribe();
          } else {
              boolean alreadyDestroyed = _destroyedSubs.remove(oid);
              if (!alreadyDestroyed) {
                  log.warning("Missing subscription in unmap", "client", this, "oid", oid);
              }
          }
      }
docs: Makes a note that this client is no longer subscribed to this object. The subscription map
  is used to clean up after the client when it goes away.