GWT: Adding a value change listener to EditTextCell widget

I want to do validation for EditTextCell widget in the grid. So I am trying to extend the EditTextCell and add a value change listener to the same, so that I can continue with the validation. But I am unable to add the same. Any help would be appreciated. Am using GWT 2.4.0

My code looks like this.

public class MyEditTextCell extends EditTextCell
 {
       //Value change listener??
 }
 

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