code: CacheBucketOffset get(long segmentId, UUID keyHash) {
          SegmentKeyCache cache;
          int generation;
          synchronized (this.segmentCaches) {
              generation = this.currentCacheGeneration;
              cache = this.segmentCaches.get(segmentId);
          }
  
          return cache == null ? null : cache.get(keyHash, generation);
      }
docs: Looks up a cached offset for the given Segment and Key Hash.
  
  @param segmentId The Id of the Segment to look up for.
  @param keyHash   A UUID representing the Key Hash to look up.
  @return A {@link CacheBucketOffset} representing the sought result.