code: private Map<String, Scope> getSubMap(Map<String, Map<String, Scope>> parent, String key) {
  
  	Map<String, Scope> context = parent.get(key);
  	if (context != null) return context;
  
  	context = MapFactory.<String, Scope>getConcurrentMap();
  	parent.put(key, context);
  	return context;
  
      }
docs: return a map matching key from given map
  
  @param parent
  @param key key of the map
  @return matching map, if no map exist it willbe one created