public void setOnDurationChangeListener(OnDurationChangedListener listener) {
        changeListener = listener;
    }
Sets a listener to be informed of updates to the entered duration.

@param listener the listener to be informed or {@code null} if no one should be informed.
android/third_party/time-duration-picker/src/main/java/mobi/upod/timedurationpicker/TimeDurationPicker.java