looking at AEM 6.5 API I found that ResponsiveGridExporter (The Adobe AEM Quickstart and Web Application.) now has additional method to implement - getAllowedComponents. This method's signature tells that an instance of com.day.cq.wcm.foundation.model.impl.exportAllowedComponentsExporter should be returned. However the com.day.cq.wcm.foundation.model.impl package is declared as private package.
I'm a little bit confused. Could anyone help me on that?