IAjaxIndicatorAware/WicketAjaxIndicatorAppender with AutoCompleteTextField doesn't work

When adding IAjaxIndicatorAware/WicketAjaxIndicatorAppender to an AutoCompleteTextField to indicate loading of remote data, the Indicator isn't activated.

On a side note: AbstractAutoCompleteBehavior#onBind adds another AbstractDefaultAjaxBehavior which is unnecessary since AbstractAutoCompleteBehavior extends that already.