What XPath version does a given Selenium WebDriver support?

SeleniumXPathVersion2.java

private String getXPathVersion(WebDriver context) {
    try {
        By.xpath("/nobody[@attr=lower-case('A')]").findElement(context);
        return "2.0";
    } catch (Exception e) {
        return "1.0";
    }
}

SeleniumXPathVersion3.java

private String getXPathVersion(WebDriver context) {
    try {
        By.xpath("/nobody[@attr=('A'||'')]").findElement(context);
        return "3.0";
    } catch (Exception e) {
        try {
            By.xpath("/nobody[@attr=lower-case('A')]").findElement(context);
            return "2.0";
        } catch (Exception e) {
            return "1.0";
        }
    }
}

See: http://acdcjunior.github.io/xpath-2-3-version-selenium-webdriver-support.html