For implementing logging in the framework, define the log object in the TestBase class, as shown here:

protected static Logger log = null;

Mark the AActionKeyword class as shown here:

public class AActionKeyword extends TestBase implements IActionKeyword

Then initialize the logger object in the OpenBrowser constructor using the following code:

log = Logger.getLogger(OpenBrowser.class);
PropertyConfigurator.configure("log4j.properties");

With this, we can incorporate the log4j logs in the OpenBrowser class, as shown here:

public class OpenBrowser extends AActionKeyword {
    public OpenBrowser() throws IOException, FilloException {
         super();
         log = Logger.getLogger(OpenBrowser.class);
         PropertyConfigurator.configure("log4j.properties");
    }
    static RemoteWebDriver driver;
    static DesiredCapabilities capabilities;
    public WebDriver openBrowser(List<String> browserName) {
    if (browserName.get(0).equalsIgnoreCase("chrome")) {
         log.info("Executing openBrowser");
         System.setProperty("webdriver.chrome.driver",
 System.getProperty("user.dir")
 + "\src\main\resources\chromedriver.exe");
        driver = new ChromeDriver();
     } else if (browserName.get(0).equalsIgnoreCase("ie")) {
         System.setProperty("webdriver.ie.driver",
 System.getProperty("user.dir")
 + "\src\main\resources\IEDriverServer.exe");
        driver = new InternetExplorerDriver();
     } else if (browserName.get(0).equalsIgnoreCase("firefox")) {
         System.setProperty("webdriver.gecko.driver",
 System.getProperty("user.dir")
 + "\src\main\resources\geckodriver.exe");
 driver = new FirefoxDriver();
     }
     return driver;
 }
}
Output:
2018-09-23 12:56:04 INFO  OpenBrowser:31 - Executing openBrowser