#vulnerable code 
                                @Override
    public void destroyAppiumNode(String host) throws IOException {
        new Api().getResponse("http://" + host + ":4567"
                + "/appium/stop").body().string();

    } 
                            #location 4 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                @Override
    public void destroyAppiumNode(String host) throws Exception {
        new Api().getResponse("http://" + host + ":" + getRemoteAppiumManagerPort(host)
                + "/appium/stop").body().string();

    }