#vulnerable code 
                                public static void premain(final String args, final Instrumentation instrumentation) {
        Map<String, String> argMap = parseArgs(args);
        String statsdServer = argMap.get("server");
        int statsdPort = Integer.valueOf(argMap.get("port"));
        String prefix = argMap.get("prefix");
        List<String> filterPackages = Arrays.asList(argMap.get("filterPackages").split(":"));

        StatsDClient client = new NonBlockingStatsDClient(prefix, statsdServer, statsdPort);

        Profiler memoryProfiler = new MemoryProfiler(client);
        Profiler cpuProfiler = new CPUProfiler(client, filterPackages);
        Collection<Profiler> profilers = Arrays.asList(memoryProfiler, cpuProfiler);

        scheduleProfilers(profilers);
        registerShutdownHook(profilers);
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public static void premain(final String args, final Instrumentation instrumentation) {
        Arguments arguments = Arguments.parseArgs(args);
        String statsdServer = arguments.statsdServer;
        int statsdPort = arguments.statsdPort;
        String prefix = arguments.metricsPrefix.or("statsd-jvm-profiler");
        List<String> filterPackages = arguments.filterPackages.or(new ArrayList<String>());

        StatsDClient client = new NonBlockingStatsDClient(prefix, statsdServer, statsdPort);

        Profiler memoryProfiler = new MemoryProfiler(client);
        Profiler cpuProfiler = new CPUProfiler(client, filterPackages);
        Collection<Profiler> profilers = Arrays.asList(memoryProfiler, cpuProfiler);

        scheduleProfilers(profilers);
        registerShutdownHook(profilers);
    }