public StateTransitionObj getPersistentCleanInstance()
{
StateTransitionObj obj = getHollowInstance();
if( obj == null ) return null;
StateTransitionObj sto = (StateTransitionObj) obj;
int val = sto.readField();
int curr = currentState(sto);
if( curr != PERSISTENT_CLEAN ) {
if (debug) {
logger.debug("StateTransition: Unable to create persistent-clean instance" +
" from a hollow instance by reading a field, state is " +