I am automating a login page. I am using the page object design pattern Selenium with Java. What should I improve on in my code?

package Pages;

import org.openqa.selenium.WebDriver;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.support.FindBy;
import org.openqa.selenium.support.PageFactory;


public class LoginPage 
{
    private WebDriver driver;

       @FindBy(id="userName")
       WebElement username;
       @FindBy(id="password")
       WebElement password;
       @FindBy(className="btn-info")
       WebElement button;
       public LoginPage(WebDriver driver)
       {
        //initialize elements
          PageFactory.initElements(driver, this);

       }
       public void set_username(String usern)
       {
        username.clear();
        username.sendKeys(usern);
       }
       public void set_password(String userp)
       {
        password.clear();
        password.sendKeys(userp);
       }
       public void click_button()
       {
        button.submit();
       }
}

package Test;
import org.testng.annotations.Test;


import Pages.LoginPage;
import org.testng.Assert;
import org.openqa.selenium.By;
import org.openqa.selenium.WebDriver;
import org.openqa.selenium.firefox.FirefoxDriver;
import org.testng.annotations.AfterTest;
import org.testng.annotations.BeforeTest;



public class LoginTest
{
WebDriver driver;
@BeforeTest
public void setup()
{
    System.setProperty("webdriver.firefox.marionette","pathToGeckodriver");
    driver=new FirefoxDriver();
    driver.manage().window().maximize();
    driver.get("https://twhyderabad.github.io/demo_site/");
}
@Test(priority=5)
public void verify1()
{
    LoginPage login=new LoginPage(driver);
    login.set_username("admin");
    login.set_password("admin");
    login.click_button();
    Assert.assertTrue(driver.getPageSource().contains("Blog"));
}
@Test(priority=1)
public void verify2()
{
    LoginPage login=new LoginPage(driver);
    login.set_username("adm");
    login.set_password("admin");
    login.click_button();
    Assert.assertEquals(driver.findElement(By.xpath("//*[@id='errorMessage']")).getText(),"Wrong username or password!");
}
@Test(priority=2)
public void verify3()
{
    LoginPage login=new LoginPage(driver);
    login.set_username("admin");
    login.set_password("adm");
    login.click_button();
    Assert.assertEquals(driver.findElement(By.xpath("//*[@id='errorMessage']")).getText(),"Wrong username or password!");
}
@Test(priority=3)
public void verify4()
{
    LoginPage login=new LoginPage(driver);
    login.set_username("adm");
    login.set_password("adm");
    login.click_button();
    Assert.assertEquals(driver.findElement(By.xpath("//*[@id='errorMessage']")).getText(),"Wrong username or password!");
}
@Test(priority=4)
public void verify5()
{
    LoginPage login=new LoginPage(driver);
    login.set_username("");
    login.set_password("");
    login.click_button();
    Assert.assertEquals(driver.findElement(By.xpath("//*[@id='errorMessage']")).getText(),"Wrong username or password!");
}
@AfterTest
public void close()
{
    driver.close();
}
}