This customfield is not an editable field but allows to identify dynamically one or more users following different rules. The goal is to identify users from another User Field of an Issue (same issue or not, from same project or not) identified by different ways.
How to configure them ?
When adding a new Customfield, select the Customfield Type Multi Users from other User Customfield :
Then, you will be able to configure your customfield :
First, you will have to identify the target Issue. It can be done by specifying :
the target Issue Type of the linked Issue :
or the Link Issue Type of the linked Issue :
or the Issue Key (stored in another field of the current Issue) : (Only Customfields are listed currently)
Secondly, you will have to specify the User Field(s) of the target Issue from which the Users have to be identified : (Only Customfields are listed currently)
And finally, you define how this users fields will be rendered (only SHOW USERS is significant for this customfield)