@SuppressWarnings("unchecked")
  static <K> Node<K> tabAt(Node<K>[] tab, int i) {
    return (Node<K>) U.getObjectVolatile(tab, ((long) i << ASHIFT) + ABASE);
  }
Returns k.compareTo(x) if x matches kc (k's screened comparable class), else 0.
geode-core/src/main/java/org/apache/geode/internal/concurrent/CompactConcurrentHashSet2.java