#vulnerable code 
                                static String rootPath() {
        String path = System.getProperty("java.io.tmpdir");
        String sep = System.getProperty("file.separator");

        if (!path.endsWith(sep)) {
            path += sep;
        }

        return path + "chronicle-log4j1";
    } 
                            #location 5 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                static String rootPath() {
        String path = OS.getTarget();
        String sep = System.getProperty("file.separator");

        if (!path.endsWith(sep)) {
            path += sep;
        }

        return path + "chronicle-log4j1" + Time.uniqueId();
    }