code: public static <MK, K, V> Map<K, V> getReadOnlyAtomicMap(Cache<MK, ?> cache, MK key) {
        AtomicMap<K, V> am = getAtomicMap(cache, key, false);
        if (am == null)
           return Collections.emptyMap();
        else
           return immutableMapWrap(am);
     }
docs: Retrieves an atomic map from a given cache, stored under a given key, for reading only.  The atomic map returned
  will not support updates, and if the map did not in fact exist, an empty map is returned.
  
  @param cache underlying cache
  @param key   key under which the atomic map exists
  @param <MK>  key param of the cache
  @param <K>   key param of the AtomicMap
  @param <V>   value param of the AtomicMap
  @return an immutable, read-only map