code: static String toIteratorCategory(String type, String link, List<String> fields) {
  		return toEntityCategory(type + "." + link, fields);
  		//return type + '.' + link;
  	}
docs: Converts an iterator category and the link name to a child iterator category.
  Iterator category is represented as String: "Type.link1.link2...". For instance "Message.Sender.Person"
  
  @param type parent iterator category
  @param link link name
  @return     child iterator category