[BACKLOG-1498] First stab at model annotation definition

Exactly. If these are aggregate types for measures, it must be the short list above. The list you have identified relates to Kettle grouping rules here: https://github.com/pentaho/pentaho-kettle/blob/9f1fa3783e37059bc70f0f3350c35dfc8e836a5d/engine/src/org/pentaho/di/trans/steps/groupby/GroupByMeta.java#L102