InternalCache getCache() {
      InternalCache result = cache;
      if (result == null) {
        throw new IllegalStateException("Missing cache instance.");
      }
      if (result.isClosed()) {
        throw new CacheClosedException();
      }
      return result;
    }
Hides cache level details and exposes simple methods relevant for auto-balancing
geode-rebalancer/src/main/java/org/apache/geode/cache/util/AutoBalancer.java