Hysterix Request Cache Design

I am trying to read up on some code to study design patterns and I came across Hysterix. I am reading this class HysterixRequestCache and it does something particular. This class is a static factory class which creates an instance of itself with the method getInstance(), but the thing I am really confused about it that it also creates a concurrenthashmap that caches itself . What design pattern is this and what is the benefit of doing it this way?

https://github.com/Netflix/Hystrix/blob/master/hystrix-core/src/main/java/com/netflix/hystrix/HystrixRequestCache.java