question: private < T > int countClearedRefs ( List < WeakReference < T > > refs ) { final Iterator < WeakReference < T > > itr = refs . iterator ( ) ; int n = 0 ; while ( itr . hasNext ( ) ) { final WeakReference < T > ref = itr . next ( ) ; if ( ref . get ( ) == null ) n ++ ; } return n ; }
target:  Return the #of entries in the collection whose references have been cleared.