This parameter (which can also be entered as 'user') filters reservations to only include those 'owned' by the provided users. To be returned, a user must be the owner of the reservation, not just an attendee. This parameter can have either a single or multiple values. For multiple values, they can be entered as a JSON formatted array of user identifier values or as a set of comma separated values. If a user identifier value contains a comma, it should be provided as a JSON array. User identifier values can be the userID (a uuid string), name, or email of the user within Maptician. Names and emails are case and punctuation sensitive, emails are case insensitive. A mix of userID, name, and email values can be used, and values referring to the same user will be treated as a single reference.