code: private void setMapForKeyGroup(int keyGroupId, Map<N, Map<K, S>> map) {
  		try {
  			state[indexToOffset(keyGroupId)] = map;
  		} catch (ArrayIndexOutOfBoundsException e) {
  			throw new IllegalArgumentException("Key group index " + keyGroupId + " is out of range of key group " +
  				"range [" + keyGroupOffset + ", " + (keyGroupOffset + state.length) + ").");
  		}
  	}
docs: Sets the given map for the given key-group.