Below is the code I tried for highlight the elements in website when executing my code, but highlight is not happening for me.
My Helper class in Utility package:
public class Helper {
    WebDriver driver;
    public Helper(WebDriver driver){
        this.driver=driver;
    }
    public void highLightElement(WebDriver driver,WebElement element){
        JavascriptExecutor jse = (JavascriptExecutor) driver;
        jse.executeScript("arguments[0].style.border='3px solid red'", element);
        try{
            Thread.sleep(500);
        }
        catch(InterruptedException e){
            System.out.println(e.getMessage());
        }
    }
}
LoginPage.java:
public class LoginPage {
    WebDriver driver;
//public Helper helper=new Helper(driver);
    WebElement Agentid=driver.findElement(By.xpath(".//*[@id='admin_value']/div[1]/input"));
    WebElement agentEmailid=driver.findElement(By.xpath(".//*[@id='admin_value']/div[2]/input"));
    WebElement agentPwd=driver.findElement(By.xpath(".//*[@id='admin_value']/div[3]/input"));
    WebElement loginbtn=driver.findElement(By.xpath(".//*[@id='admin_value']/input"));
    public LoginPage(WebDriver driver){
        this.driver=driver;
    }
    public void AgentLogin(String agentid,String agent_emailid,String password){
        Helper helper=new Helper(driver);
        helper.highLightElement(driver, Agentid);
        Agentid.sendKeys(agentid);
        helper.highLightElement(driver, agentEmailid);
        agentEmailid.sendKeys(agent_emailid);
        helper.highLightElement(driver, agentPwd);
        agentPwd.sendKeys(password);
        helper.highLightElement(driver, loginbtn);
        loginbtn.click();       
    }
}
LoginPageActions.java:
public class LoginPageActions {
    WebDriver driver;   
    /*public LoginPageActions(WebDriver driver){
        this.driver=driver;
    }*/ 
    @BeforeClass
    public void startup(){
        System.setProperty("webdriver.gecko.driver","D://Krishna//geckodriver-v0.11.1-win32//geckodriver.exe");
        System.setProperty("webdriver.chrome.driver", "D://Krishna//chromedriver_win32//chromedriver.exe");
            driver=new ChromeDriver();
            driver.navigate().to("http://************");
            driver.manage().window().maximize();
    }
    @Test(priority=1)
    public void Login(){        
        LoginPage login=new LoginPage(driver);      
        login.AgentLogin("100", "krishna@yahoo.com", "abc");        
        HomePage home=new HomePage(driver);
        home.click_SignOut();
    }
Output:
FAILED: Login
===============================================
    Default test
    Tests run: 1, Failures: 1, Skips: 0
===============================================
Showing Error as -java.lang.NullPointerException
