called when an action has been found , but the request parsing has failed . the default behavior is to render the framework 's default 400 page . this is achieved by returning null , so that the scala engine handles onbadrequest . by overriding this method one can provide an alternative 400 page . concode_field_sep PlaceHolder placeHolder concode_field_sep void onStart concode_elem_sep F.Promise<Result> onError concode_elem_sep Action onRequest concode_elem_sep void beforeStart concode_elem_sep F.Promise<Result> onHandlerNotFound concode_elem_sep Class<T>[] filters concode_elem_sep play.api.mvc.Handler onRouteRequest concode_elem_sep Configuration onLoadConfig concode_elem_sep Configuration onLoadConfig concode_elem_sep void onStop
F . Promise < Result > function ( RequestHeader arg0 , String arg1 ) { return null ; }