docs: @SuppressWarnings({ "unchecked" })
      /* package */<T> HystrixCachedObservable<T> get(String cacheKey) {
          ValueCacheKey key = getRequestCacheKey(cacheKey);
          if (key != null) {
              ConcurrentHashMap<ValueCacheKey, HystrixCachedObservable<?>> cacheInstance = requestVariableForCache.get(concurrencyStrategy);
              if (cacheInstance == null) {
                  throw new IllegalStateException("Request caching is not available. Maybe you need to initialize the HystrixRequestContext?");
              }
              /* look for the stored value */
              return (HystrixCachedObservable<T>) cacheInstance.get(key);
          }
          return null;
      }