question: private void traceObject ( ObjectReference object , boolean root ) { if ( VERBOSE ) { Trace . trace ( Item . SANITY , "tracing object %s" , ObjectModel . getString ( object ) ) ; } if ( object . isNull ( ) ) return ; boolean marked = blackSet . contains ( object ) ; if ( ! marked ) { blackSet . add ( object ) ; markStack . add ( object ) ; } visitor . visitObject ( object , root , marked ) ; }
target:  Trace an object, calling the appropriate visitor method