#vulnerable code 
                                @SuppressWarnings("unused")
    static void onTimeoutNowReturned(final ThreadId id, final Status status, final TimeoutNowRequest request,
                                     final TimeoutNowResponse response, final boolean stopAfterFinish) {
        final Replicator r = (Replicator) id.lock();
        if (r == null) {
            return;
        }

        final boolean isLogDebugEnabled = LOG.isDebugEnabled();
        StringBuilder sb = null;
        if (isLogDebugEnabled) {
            sb = new StringBuilder("Node "). //
                append(r.options.getGroupId()).append(":").append(r.options.getServerId()). //
                append(" received TimeoutNowResponse from "). //
                append(r.options.getPeerId());
        }
        if (!status.isOk()) {
            if (isLogDebugEnabled) {
                sb.append(" fail:").append(status);
                LOG.debug(sb.toString());
            }
            if (stopAfterFinish) {
                r.notifyOnCaughtUp(RaftError.ESTOP.getNumber(), true);
                r.destroy();
            } else {
                id.unlock();
            }
            return;
        }
        if (isLogDebugEnabled) {
            sb.append(response.getSuccess() ? " success" : " fail");
            LOG.debug(sb.toString());
        }
        if (response.getTerm() > r.options.getTerm()) {
            final NodeImpl node = r.options.getNode();
            r.notifyOnCaughtUp(RaftError.EPERM.getNumber(), true);
            r.destroy();
            node.increaseTermTo(response.getTerm(), new Status(RaftError.EHIGHERTERMRESPONSE,
                "Leader receives higher term timeout_now_response from peer:%s", r.options.getPeerId()));
            return;
        }
        if (stopAfterFinish) {
            r.notifyOnCaughtUp(RaftError.ESTOP.getNumber(), true);
            r.destroy();
        } else {
            id.unlock();
        }

    } 
                            #location 38 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @SuppressWarnings("unused")
    static void onTimeoutNowReturned(final ThreadId id, final Status status, final TimeoutNowRequest request,
                                     final TimeoutNowResponse response, final boolean stopAfterFinish) {
        final Replicator r = (Replicator) id.lock();
        if (r == null) {
            return;
        }

        final boolean isLogDebugEnabled = LOG.isDebugEnabled();
        StringBuilder sb = null;
        if (isLogDebugEnabled) {
            sb = new StringBuilder("Node "). //
                append(r.options.getGroupId()).append(":").append(r.options.getServerId()). //
                append(" received TimeoutNowResponse from "). //
                append(r.options.getPeerId());
        }
        if (!status.isOk()) {
            if (isLogDebugEnabled) {
                sb.append(" fail:").append(status);
                LOG.debug(sb.toString());
            }
            notifyReplicatorStatusListener(r, ReplicatorEvent.ERROR, status);
            if (stopAfterFinish) {
                r.notifyOnCaughtUp(RaftError.ESTOP.getNumber(), true);
                r.destroy();
            } else {
                id.unlock();
            }
            return;
        }
        if (isLogDebugEnabled) {
            sb.append(response.getSuccess() ? " success" : " fail");
            LOG.debug(sb.toString());
        }
        if (response.getTerm() > r.options.getTerm()) {
            final NodeImpl node = r.options.getNode();
            r.notifyOnCaughtUp(RaftError.EPERM.getNumber(), true);
            r.destroy();
            node.increaseTermTo(response.getTerm(), new Status(RaftError.EHIGHERTERMRESPONSE,
                "Leader receives higher term timeout_now_response from peer:%s", r.options.getPeerId()));
            return;
        }
        if (stopAfterFinish) {
            r.notifyOnCaughtUp(RaftError.ESTOP.getNumber(), true);
            r.destroy();
        } else {
            id.unlock();
        }

    }