Hi! Found some inconsistency between behavior and documentation: when adding stem_dictionary to a field, it enables stem: true automatically. From the doc it seems that it an option, not a requirement:

Yes this needs clarification. When you set just "stem: true" the stemming is using the porter stemmer. With dictionary stemming is using the dictionary definitions. Technically both are stemming which is why stem is set to true even when only dictionary is defined in schema.