java.lang.ExceptionInInitializerError while initializing Page Factory

I am making POM framework with Page Factory and while initializing Page Factory with PageFactory.initElements(new AppiumFieldDecorator(driver),this) it is throwing Exception as
java.lang.ExceptionInInitializerError
at io.appium.java_client.pagefactory.utils.ProxyFactory.getEnhancedProxy(ProxyFactory.java:52)

I am using
Appium-1.6.2
Java Client-6.1.0

Changing the MobileElement to WebElement in the PageObject Class fixed this issue for me.