code: public void assignTypes(XEvent event, Map<List<String>, String> types) {
  		XCostType.instance().assignNestedValues(event, types);
  	}
docs: Assigns (to the given event) multiple cost types given their keys.
  Note that as a side effect this method
  creates attributes when it does not find an attribute with the proper
  key.
  
  @see #assignAmounts(XEvent, Map)
  
  @param event
  Event to assign the cost types to.
  @param types
  Mapping from keys to cost types which are to be assigned.