/** {@inheritDoc} */
 @Override
 public void saveCheckpoint(String key, Object state, GridTaskSessionScope scope, long timeout)
     throws GridException {
   saveCheckpoint(key, state, scope, timeout, true);
 }
 /** {@inheritDoc} */
 @Override
 public void saveCheckpoint(String key, Object state) throws GridException {
   saveCheckpoint(key, state, GridTaskSessionScope.SESSION_SCOPE, 0);
 }