This is a LRU cache that has no performance impact for cache insertions once the capacity of the cache has been reached. For cache hit, performance is O(1) and for cache eviction, it is O(1).
HashMap get is O(1). More info: https://stackoverflow.com/a/4578039/2085356
HashMap put and remove is O(1). More info: https://stackoverflow.com/a/4578039/2085356