Java 8 Features Comprehensive Guide

I am looking for an individual well-versed in all the features released on Java 8 for a four-hour stint. You'll be required to utilise your deep knowledge pertaining to Lambdas, Streams, Optional, and Default methods among others.

* Key Skills Required:
- Extensive knowledge and experience with Java 8
- Deep understanding of Lambdas, Streams, Optional, and Default Methods
- Ability to convey complex concepts succinctly and clearly

Although the timeframe for project completion was unmarked, I would appreciate a speedy delivery without compromising quality.