They will check your logical understanding by asking some algo e.g. sorting, searching algos and difficulty will depend on your exp. In my case array was given and interviewer asked me to do sorting with any algo.

I was asked about singleton, factory and DAO design pattern as they were on my CV.

JavaScript basic knowledge like diff between == and ===..

There was no quest on threading but they can ask , It depends... He asked me How internally Hashmap works..,. no other quest from collection but one should be prepared... with threading collection and generics.. and there were questions from my CV like MVC architecture and stuff so you can prepare your CV according to your knowledge and instead of putting generic terms just go with the specific API or implementations you have done. So they will directly jump on these things and will check if you know or not the things you written in your CV..