Need to use API of WebDriver/RemoteWebDriver with the driver initiated by Appium/AndroidDriver

Case 1: When using AndroidDriver object and calling WebDriver method "click"

import java.net.MalformedURLException;
import java.net.URL;
import java.util.concurrent.TimeUnit;
import org.openqa.selenium.By;
import org.openqa.selenium.WebElement;
import org.openqa.selenium.remote.DesiredCapabilities;
import org.openqa.selenium.remote.RemoteWebDriver;
import io.appium.java_client.android.AndroidDriver;

public class TestApp
{
static RemoteWebDriver rDriver = null;
public static void main(String args[]) throws MalformedURLException
{
DesiredCapabilities capabilities = new DesiredCapabilities();
capabilities.setCapability(“device”,“Android”);
capabilities.setCapability(“app”, “healthkart_prod.apk”);
capabilities.setCapability(“pltformName”, “ANDROID”);
capabilities.setCapability(“appPackage”, “com.healthkart.healthkart”);
capabilities.setCapability(“appActivity”, “com.healthkart.healthkart.Splash”);
capabilities.setCapability(“app”, “E:/healthkart_prod.apk”);
capabilities.setCapability(“deviceName”, “Android”);
capabilities.setCapability(“platformName”, “Android”);

    AndroidDriver<WebElement> androidDriver = new AndroidDriver<WebElement>(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);
    
    androidDriver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
    try
    {
    WebElement element = androidDriver.findElement(By.xpath("//android.widget.ImageButton[@content-desc='Navigate up']"));
    element.click();
    }
    catch(Exception e)
    {
    	e.printStackTrace();
    }
}

}

Getting following exception:-
java.lang.NullPointerException
at org.openqa.selenium.remote.RemoteWebElement.execute(RemoteWebElement.java:279)
at org.openqa.selenium.remote.RemoteWebElement.click(RemoteWebElement.java:83)
at com.healthkart.hkMsiteAutomation.regression.TestApp.main(TestApp.java:35)

Case 2:

    AndroidDriver<WebElement> driver = new AndroidDriver<WebElement>(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);
    rDriver = driver;
    
    driver.manage().timeouts().implicitlyWait(60, TimeUnit.SECONDS);
    try
    {
    WebElement element = rDriver.findElement(By.xpath("//android.widget.ImageButton[@content-desc='Navigate up']"));
    element.click();
    }
    catch(Exception e)
    {
    	e.printStackTrace();
    }
}

Still getting same exception

CASE 3:

WebElement element = driver.findElement(By.xpath("//android.widget.ImageButton[@content-desc=‘Navigate up’]"));
driver.tap(1, element, 1);

Working fine for me. But the bottomline is that I am able to call methods of WebDriver but getting the above exception.

Try

AppiumDriver<WebElement> androidDriver = new AndroidDriver<WebElement>(new URL("http://127.0.0.1:4723/wd/hub"), capabilities);