How to take a screenshot in firefox headless (selenium in java)?

I have been able to run a selenium test case with headless Firefox, However when taking a screenshot, the screenshot is not that of the web-page(web-page tested in the testcase) rather, the screenshot is taken of the background (as in. the current window shown (e.g. eclipse IDE running the testcase))

Screenshot function

File screenShotFolder = new File("Screenshots");
        WebDriver driver = getDriver();
        try {
            if (!screenShotFolder.exists() && !screenShotFolder.mkdir()) {
                getLog().error(
                        "Cannot create a new file in the intended location. "
                                + "" + screenShotFolder.getAbsolutePath());
            }
            File scrFile =
                    ((TakesScreenshot) driver).getScreenshotAs(OutputType.FILE);
            String filePath =
                    screenShotFolder.getAbsolutePath() + File.separator
                            + imageName + ".png";
            FileUtils.copyFile(scrFile, new File(filePath));

        } catch (Exception e) {
            e.printStackTrace();
        }

is there any other "options" or "arguments" that need to be set?

Taking a screenshot with headless Firefox should work like for usual driver.

In the past I used the following approach:

public static String makeScreenshot() {
    String fileName = System.currentTimeMillis() + "Test";
    File screenshot = Driver.driver.get().getScreenshotAs(OutputType.FILE);
    File outputFile = new File("LoggerScreenshots/" + fileName + ".png");
    System.out.println(outputFile.getAbsolutePath());
    try {
        FileUtils.copyFile(screenshot, outputFile);
    } catch (IOException e) {
        e.printStackTrace();
    }
    return outputFile.getName();
}

And called it when test execution fails: