#fixed code
                                synchronized boolean connect(final TransactionContext transactionContext) throws EventHubException {
        if (connected) {
            logger.warn(format("%s already connected.", toString()));
            return true;
        }
        eventStream = null;

        final CountDownLatch finishLatch = new CountDownLatch(1);

        logger.debug(format("EventHub %s is connecting.", name));

        lastConnectedAttempt = System.currentTimeMillis();

        Endpoint endpoint = new Endpoint(url, properties);
        managedChannel = endpoint.getChannelBuilder().build();

        clientTLSCertificateDigest = endpoint.getClientTLSCertificateDigest();

        events = EventsGrpc.newStub(managedChannel);

        final ArrayList<Throwable> threw = new ArrayList<>();

        final StreamObserver<PeerEvents.Event> eventStreamLocal = new StreamObserver<PeerEvents.Event>() {
            @Override
            public void onNext(PeerEvents.Event event) {

                logger.debug(format("EventHub %s got  event type: %s", EventHub.this.name, event.getEventCase().name()));

                if (event.getEventCase() == PeerEvents.Event.EventCase.BLOCK) {
                    try {
                        eventQue.addBEvent(new BlockEvent(EventHub.this, event));  //add to channel queue
                    } catch (InvalidProtocolBufferException e) {
                        EventHubException eventHubException = new EventHubException(format("%s onNext error %s", this, e.getMessage()), e);
                        logger.error(eventHubException.getMessage());
                        threw.add(eventHubException);
                    }
                } else if (event.getEventCase() == PeerEvents.Event.EventCase.REGISTER) {

                    connected = true;
                    connectedTime = System.currentTimeMillis();
                    finishLatch.countDown();
                }
            }

            @Override
            public void onError(Throwable t) {
                if (shutdown) { //IF we're shutdown don't try anything more.
                    logger.trace(format("%s was shutdown.", EventHub.this.toString()));
                    connected = false;
                    eventStream = null;
                    finishLatch.countDown();
                    return;
                }

                final boolean isTerminated = managedChannel.isTerminated();
                final boolean isChannelShutdown = managedChannel.isShutdown();

                logger.error(format("%s terminated is %b shutdown is %b has error %s ", EventHub.this.toString(), isTerminated, isChannelShutdown,
                        t.getMessage()), new EventHubException(t));
                threw.add(t);
                finishLatch.countDown();

                //              logger.error("Error in stream: " + t.getMessage(), new EventHubException(t));
                if (t instanceof StatusRuntimeException) {
                    StatusRuntimeException sre = (StatusRuntimeException) t;
                    Status sreStatus = sre.getStatus();
                    logger.error(format("%s :StatusRuntimeException Status %s.  Description %s ", EventHub.this, sreStatus + "", sreStatus.getDescription()));
                    if (sre.getStatus().getCode() == Status.Code.INTERNAL || sre.getStatus().getCode() == Status.Code.UNAVAILABLE) {

                        connected = false;
                        eventStream = null;
                        disconnectedTime = System.currentTimeMillis();
                        try {
                            if (!isChannelShutdown) {
                                managedChannel.shutdownNow();
                            }
                            if (null != disconnectedHandler) {
                                try {
                                    disconnectedHandler.disconnected(EventHub.this);
                                } catch (Exception e) {
                                    logger.warn(format("Eventhub %s  %s", EventHub.this.name, e.getMessage()), e);
                                    eventQue.eventError(e);
                                }
                            }
                        } catch (Exception e) {
                            logger.warn(format("Eventhub %s Failed shutdown msg:  %s", EventHub.this.name, e.getMessage()), e);
                        }
                    }
                }

            }

            @Override
            public void onCompleted() {

                logger.warn(format("Stream completed %s", EventHub.this.toString()));
                finishLatch.countDown();

            }
        };

        sender = events.chat(eventStreamLocal);
        try {
            blockListen(transactionContext);
        } catch (CryptoException e) {
            throw new EventHubException(e);
        }

        try {
            if (!finishLatch.await(EVENTHUB_CONNECTION_WAIT_TIME, TimeUnit.MILLISECONDS)) {
                EventHubException evh = new EventHubException(format("EventHub %s failed to connect in %s ms.", name, EVENTHUB_CONNECTION_WAIT_TIME));
                logger.debug(evh.getMessage(), evh);

                throw evh;
            }
            logger.trace(format("Eventhub %s Done waiting for reply!", name));

        } catch (InterruptedException e) {
            logger.error(e);
        }

        if (!threw.isEmpty()) {
            eventStream = null;
            connected = false;
            Throwable t = threw.iterator().next();

            EventHubException evh = new EventHubException(t.getMessage(), t);
            logger.error(format("EventHub %s Error in stream. error: " + t.getMessage(), toString()), evh);
            throw evh;

        }

        logger.debug(format("Eventhub %s connect is done with connect status: %b ", name, connected));

        if (connected) {
            eventStream = eventStreamLocal;
        }

        return connected;

    }
#vulnerable code 
                                synchronized boolean connect(final TransactionContext transactionContext) throws EventHubException {
        if (connected) {
            logger.warn(format("%s already connected.", toString()));
            return true;
        }
        eventStream = null;

        final CountDownLatch finishLatch = new CountDownLatch(1);

        logger.debug(format("EventHub %s is connecting.", name));

        lastConnectedAttempt = System.currentTimeMillis();

        managedChannel = new Endpoint(url, properties).getChannelBuilder().build();

        events = EventsGrpc.newStub(managedChannel);

        final ArrayList<Throwable> threw = new ArrayList<>();

        final StreamObserver<PeerEvents.Event> eventStreamLocal = new StreamObserver<PeerEvents.Event>() {
            @Override
            public void onNext(PeerEvents.Event event) {

                logger.debug(format("EventHub %s got  event type: %s", EventHub.this.name, event.getEventCase().name()));

                if (event.getEventCase() == PeerEvents.Event.EventCase.BLOCK) {
                    try {
                        eventQue.addBEvent(new BlockEvent(EventHub.this, event));  //add to channel queue
                    } catch (InvalidProtocolBufferException e) {
                        EventHubException eventHubException = new EventHubException(format("%s onNext error %s", this, e.getMessage()), e);
                        logger.error(eventHubException.getMessage());
                        threw.add(eventHubException);
                    }
                } else if (event.getEventCase() == PeerEvents.Event.EventCase.REGISTER) {

                    connected = true;
                    connectedTime = System.currentTimeMillis();
                    finishLatch.countDown();
                }
            }

            @Override
            public void onError(Throwable t) {
                if (shutdown) { //IF we're shutdown don't try anything more.
                    logger.trace(format("%s was shutdown.", EventHub.this.toString()));
                    connected = false;
                    eventStream = null;
                    finishLatch.countDown();
                    return;
                }

                final boolean isTerminated = managedChannel.isTerminated();
                final boolean isChannelShutdown = managedChannel.isShutdown();

                logger.error(format("%s terminated is %b shutdown is %b has error %s ", EventHub.this.toString(), isTerminated, isChannelShutdown,
                        t.getMessage()), new EventHubException(t));
                threw.add(t);
                finishLatch.countDown();

                //              logger.error("Error in stream: " + t.getMessage(), new EventHubException(t));
                if (t instanceof StatusRuntimeException) {
                    StatusRuntimeException sre = (StatusRuntimeException) t;
                    Status sreStatus = sre.getStatus();
                    logger.error(format("%s :StatusRuntimeException Status %s.  Description %s ", EventHub.this, sreStatus + "", sreStatus.getDescription()));
                    if (sre.getStatus().getCode() == Status.Code.INTERNAL || sre.getStatus().getCode() == Status.Code.UNAVAILABLE) {

                        connected = false;
                        eventStream = null;
                        disconnectedTime = System.currentTimeMillis();
                        try {
                            if (!isChannelShutdown) {
                                managedChannel.shutdownNow();
                            }
                            if (null != disconnectedHandler) {
                                try {
                                    disconnectedHandler.disconnected(EventHub.this);
                                } catch (Exception e) {
                                    logger.warn(format("Eventhub %s  %s", EventHub.this.name, e.getMessage()), e);
                                    eventQue.eventError(e);
                                }
                            }
                        } catch (Exception e) {
                            logger.warn(format("Eventhub %s Failed shutdown msg:  %s", EventHub.this.name, e.getMessage()), e);
                        }
                    }
                }

            }

            @Override
            public void onCompleted() {

                logger.warn(format("Stream completed %s", EventHub.this.toString()));
                finishLatch.countDown();

            }
        };

        sender = events.chat(eventStreamLocal);
        try {
            blockListen(transactionContext);
        } catch (CryptoException e) {
            throw new EventHubException(e);
        }

        try {
            if (!finishLatch.await(EVENTHUB_CONNECTION_WAIT_TIME, TimeUnit.MILLISECONDS)) {
                EventHubException evh = new EventHubException(format("EventHub %s failed to connect in %s ms.", name, EVENTHUB_CONNECTION_WAIT_TIME));
                logger.debug(evh.getMessage(), evh);

                throw evh;
            }
            logger.trace(format("Eventhub %s Done waiting for reply!", name));

        } catch (InterruptedException e) {
            logger.error(e);
        }

        if (!threw.isEmpty()) {
            eventStream = null;
            connected = false;
            Throwable t = threw.iterator().next();

            EventHubException evh = new EventHubException(t.getMessage(), t);
            logger.error(format("EventHub %s Error in stream. error: " + t.getMessage(), toString()), evh);
            throw evh;

        }

        logger.debug(format("Eventhub %s connect is done with connect status: %b ", name, connected));

        if (connected) {
            eventStream = eventStreamLocal;
        }

        return connected;

    } 
                            #location 14 
                            #vulnerability type NULL_DEREFERENCE