#fixed code
                                public void handleReference(Reference<?> ref) {

        poolLock.lock();
        try {

            if (ref instanceof BasicPoolEntryRef) {
                // check if the GCed pool entry was still in use
                //@@@ find a way to detect this without lookup
                //@@@ flag in the BasicPoolEntryRef, to be reset when freed?
                final boolean lost = issuedConnections.remove(ref);
                if (lost) {
                    final HttpRoute route =
                        ((BasicPoolEntryRef)ref).getRoute();
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Connection garbage collected. " + route);
                    }
                    handleLostEntry(route);
                }
            }

        } finally {
            poolLock.unlock();
        }
    }
#vulnerable code 
                                public void handleReference(Reference<?> ref) {

        poolLock.lock();
        try {

            if (ref instanceof BasicPoolEntryRef) {
                // check if the GCed pool entry was still in use
                //@@@ find a way to detect this without lookup
                //@@@ flag in the BasicPoolEntryRef, to be reset when freed?
                final boolean lost = issuedConnections.remove(ref);
                if (lost) {
                    final HttpRoute route =
                        ((BasicPoolEntryRef)ref).getRoute();
                    if (LOG.isDebugEnabled()) {
                        LOG.debug("Connection garbage collected. " + route);
                    }
                    handleLostEntry(route);
                }
            } else if (ref instanceof ConnMgrRef) {
                if (LOG.isDebugEnabled()) {
                    LOG.debug("Connection manager garbage collected.");
                }
                shutdown();
            }

        } finally {
            poolLock.unlock();
        }
    } 
                            #location 23 
                            #vulnerability type THREAD_SAFETY_VIOLATION