Cache

• Added Caffeine.evictionListener which is notified within the atomic operation when an entry is automatically removed
• Added triggering cache maintenance if an iterator observes an expired entry for more aggressive eviction (#487)
• Improved eager eviction of an added or updated entry if it exceeds the cache's maximum weight
• Deprecated CacheWriter. Please use asMap computations or an eviction listener instead
• Added CacheStats.of(...) to allow for becoming a value-based class in a future release