#vulnerable code 
                                @Override
    public void updateProviders(ProviderGroup providerGroup) {
        checkProviderInfo(providerGroup);
        ProviderGroup oldProviderGroup = addressHolder.getProviderGroup(providerGroup.getName());
        if (ProviderHelper.isEmpty(providerGroup)) {
            addressHolder.updateProviders(providerGroup);
            if (CommonUtils.isNotEmpty(oldProviderGroup.getProviderInfos())) {
                if (LOGGER.isWarnEnabled(consumerConfig.getAppName())) {
                    LOGGER.warnWithApp(consumerConfig.getAppName(), "Provider list is emptied, may be all " +
                        "providers has been closed, or this consumer has been add to blacklist");
                    closeTransports();
                }
            }
        } else {
            addressHolder.updateProviders(providerGroup);
            connectionHolder.updateProviders(providerGroup);
        }
        if (EventBus.isEnable(ProviderInfoUpdateEvent.class)) {
            ProviderInfoUpdateEvent event = new ProviderInfoUpdateEvent(consumerConfig, oldProviderGroup, providerGroup);
            EventBus.post(event);
        }
    } 
                            #location 3 
                            #vulnerability type THREAD_SAFETY_VIOLATION
#fixed code
                                @Override
    public void updateProviders(ProviderGroup providerGroup) {
        checkProviderInfo(providerGroup);
        ProviderGroup oldProviderGroup = addressHolder.getProviderGroup(providerGroup.getName());
        if (ProviderHelper.isEmpty(providerGroup)) {
            addressHolder.updateProviders(providerGroup);
            if (!ProviderHelper.isEmpty(oldProviderGroup)) {
                if (LOGGER.isWarnEnabled(consumerConfig.getAppName())) {
                    LOGGER.warnWithApp(consumerConfig.getAppName(), "Provider list is emptied, may be all " +
                        "providers has been closed, or this consumer has been add to blacklist");
                    closeTransports();
                }
            }
        } else {
            addressHolder.updateProviders(providerGroup);
            connectionHolder.updateProviders(providerGroup);
        }
        if (EventBus.isEnable(ProviderInfoUpdateEvent.class)) {
            ProviderInfoUpdateEvent event = new ProviderInfoUpdateEvent(consumerConfig, oldProviderGroup, providerGroup);
            EventBus.post(event);
        }
    }