#fixed code
                                @BeforeClass
    public static void beforeClass() {
        File[] traceFiles = customFileLog("").listFiles();
        if (traceFiles == null) {
            return;
        }
        for (File file : traceFiles) {
            if (file.getPath().contains("tracer-self.log") || file.getPath().contains("sync.log")
                || file.getPath().contains("rpc-profile.log")
                || file.getPath().contains("middleware_error.log")) {
                continue;
            }
            FileUtils.deleteQuietly(file);
        }
    }
#vulnerable code 
                                @BeforeClass
    public static void beforeClass() {
        for (File file : customFileLog("").listFiles()) {
            if (file.getPath().contains("tracer-self.log") || file.getPath().contains("sync.log")
                || file.getPath().contains("rpc-profile.log")
                || file.getPath().contains("middleware_error.log")) {
                continue;
            }
            FileUtils.deleteQuietly(file);
        }
    } 
                            #location 3 
                            #vulnerability type NULL_DEREFERENCE