#vulnerable code 
                                public String startContainer(DockerContainer dockerContainer)
            throws DockerException, InterruptedException {
        String imageId = dockerContainer.getImageId();
        log.info("Starting Docker container {}", imageId);
        com.spotify.docker.client.messages.HostConfig.Builder hostConfigBuilder = HostConfig
                .builder();
        com.spotify.docker.client.messages.ContainerConfig.Builder containerConfigBuilder = ContainerConfig
                .builder();

        boolean privileged = dockerContainer.isPrivileged();
        if (privileged) {
            log.trace("Using privileged mode");
            hostConfigBuilder.privileged(true);
        }
        Optional<String> network = dockerContainer.getNetwork();
        if (network.isPresent()) {
            log.trace("Using network: {}", network.get());
            hostConfigBuilder.networkMode(network.get());
        }
        Optional<Map<String, List<PortBinding>>> portBindings = dockerContainer
                .getPortBindings();
        if (portBindings.isPresent()) {
            log.trace("Using port bindings: {}", portBindings.get());
            hostConfigBuilder.portBindings(portBindings.get());
            containerConfigBuilder.exposedPorts(portBindings.get().keySet());
        }
        Optional<List<String>> binds = dockerContainer.getBinds();
        if (binds.isPresent()) {
            log.trace("Using binds: {}", binds.get());
            hostConfigBuilder.binds(binds.get());
        }
        Optional<List<String>> envs = dockerContainer.getEnvs();
        if (envs.isPresent()) {
            log.trace("Using envs: {}", envs.get());
            containerConfigBuilder.env(envs.get());
        }
        Optional<List<String>> cmd = dockerContainer.getCmd();
        if (cmd.isPresent()) {
            log.trace("Using cmd: {}", cmd.get());
            containerConfigBuilder.cmd(cmd.get());
        }
        Optional<List<String>> entryPoint = dockerContainer.getEntryPoint();
        if (entryPoint.isPresent()) {
            log.trace("Using entryPoint: {}", entryPoint.get());
            containerConfigBuilder.entrypoint(entryPoint.get());
        }

        ContainerConfig createContainer = containerConfigBuilder.image(imageId)
                .hostConfig(hostConfigBuilder.build()).build();
        String containerId = dockerClient.createContainer(createContainer).id();
        dockerClient.startContainer(containerId);

        boolean isPrivileged = dockerClient.inspectContainer(containerId)
                .hostConfig().privileged();
        log.debug("Docker container {} is running in privileged mode: {}",
                imageId, isPrivileged);

        return containerId;
    } 
                            #location 54 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public String startContainer(DockerContainer dockerContainer)
            throws DockerException, InterruptedException {
        String imageId = dockerContainer.getImageId();
        log.info("Starting Docker container {}", imageId);
        com.spotify.docker.client.messages.HostConfig.Builder hostConfigBuilder = HostConfig
                .builder();
        com.spotify.docker.client.messages.ContainerConfig.Builder containerConfigBuilder = ContainerConfig
                .builder();

        boolean privileged = dockerContainer.isPrivileged();
        if (privileged) {
            log.trace("Using privileged mode");
            hostConfigBuilder.privileged(true);
        }
        Optional<String> network = dockerContainer.getNetwork();
        if (network.isPresent()) {
            log.trace("Using network: {}", network.get());
            hostConfigBuilder.networkMode(network.get());
        }
        Optional<Map<String, List<PortBinding>>> portBindings = dockerContainer
                .getPortBindings();
        if (portBindings.isPresent()) {
            log.trace("Using port bindings: {}", portBindings.get());
            hostConfigBuilder.portBindings(portBindings.get());
            containerConfigBuilder.exposedPorts(portBindings.get().keySet());
        }
        Optional<List<String>> binds = dockerContainer.getBinds();
        if (binds.isPresent()) {
            log.trace("Using binds: {}", binds.get());
            hostConfigBuilder.binds(binds.get());
        }
        Optional<List<String>> envs = dockerContainer.getEnvs();
        if (envs.isPresent()) {
            log.trace("Using envs: {}", envs.get());
            containerConfigBuilder.env(envs.get());
        }
        Optional<List<String>> cmd = dockerContainer.getCmd();
        if (cmd.isPresent()) {
            log.trace("Using cmd: {}", cmd.get());
            containerConfigBuilder.cmd(cmd.get());
        }
        Optional<List<String>> entryPoint = dockerContainer.getEntryPoint();
        if (entryPoint.isPresent()) {
            log.trace("Using entryPoint: {}", entryPoint.get());
            containerConfigBuilder.entrypoint(entryPoint.get());
        }

        ContainerConfig createContainer = containerConfigBuilder.image(imageId)
                .hostConfig(hostConfigBuilder.build()).build();
        String containerId = dockerClient.createContainer(createContainer).id();
        dockerClient.startContainer(containerId);

        return containerId;
    }