cms.combiner.beforePrepare

Provides an opportunity to interact with the asset combiner before assets are combined.

NOTE: Plugin's must be elevated ($elevated = true on Plugin.php) to be run on the /combine route and thus listen to this event

Example usage:

Event::listen('cms.combiner.beforePrepare', function ((\System\Classes\CombineAssets) $assetCombiner, (array) $assets) {
    $assetCombiner->registerFilter(...)
});