#vulnerable code 
                                @Override
    public void readComplete(int rc, LedgerHandle lh, Enumeration<LedgerEntry> seq, Object ctx) {
        if(rc != BKException.Code.OK) fail("Return code is not OK: " + rc);

        ls = seq;

        synchronized (sync) {
            sync.value = true;
            sync.notify();
        }
    } 
                            #location 7 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public void readComplete(int rc, LedgerHandle lh, Enumeration<LedgerEntry> seq, Object ctx) {
        SyncObj sync = (SyncObj) ctx;
        sync.setLedgerEntries(seq);
        sync.setReturnCode(rc);
        synchronized (sync) {
            sync.value = true;
            sync.notify();
        }
    }