Why do I need to specify schema for ACTION_PACKAGE_ADDED intent filters?

In my app, I'm trying to listen to broadcast intents with action ACTION_PACKAGE_ADDED. But unless I also specify data schema package, 开发者_运维技巧my broadcast receiver doesn't ever get activated. Why do I need to specify the data schema?

Because the Intent that is broadcast has a Uri, and Intent resolution rules dictate that you must have a filter that matches the Uri.