How do you get all aliases (and their respective indices) in ES on 2.X?

That method is asking me for arguments. I dug in a little and it looks like it is for finding specific aliases in the system. I need them all.

Isn't there a method that just looks at the db and says "Give me all the aliases you know about"?

curl 'localhost:9200/_cat/aliases?v

gives me everything I want, but I need the Java form of it.