contentDescription is null even when the app source shows there is some thing is specified

I am trying to test a Flutter application with Appium 2.0.0.beta 57, using Java 15. I created a web element like here
@AndroidFindBy(className = “android.widget.Button”)
// @iOSXCUITFindBy(iOSNsPredicate = “type == "XCUIElementTypeTextField"”)
private WebElement scanQRCodeBtn;

The Appium Inspector is showing the following attributes

content-desc–>scan qr code|

The Java code is given below
String txt = getContentDesc(scanQRCodeBtn);

The last print out to the console is printing

What is the important thing, I might be missing here?

Thanks for your help in advance