StripedLruCache(capacity 4, 2 stripes): even keys -> stripe 0, odd keys -> stripe 1
===================================================================================

put(1) put(0) put(2) put(4)     // key 1 is the globally least recently used
get(0) -> null   (evicted: stripe 0 held {0,2} and was full)
get(1) -> present (a strict global LRU would have evicted it instead)
size() = 3 of capacity 4  (evicted while not full)