When you add this post-function to a transition and trigger the transition, the add-on sets the specified entity property of the current issue, current issue's project or current user to the specified value. The value can be provided either as text (with optional Nunjucks annotations) or as a JSON value.
In the case of text, it can be a simple string (for text typed fields), the string representation of a number, date or boolean value, or the string representation of a complex value, such as a Version name, a username, a Project key, etc. You can also use Nunjucks annotations to insert issue, transition and current user information into the value, using the 'issue', 'transition' and 'currentUser' variables, respectively.
In the case of a JSON value, which requires the option Treat value as JSON (explained below), it can be a String, a Number, a Boolean or an Object. It can also be an array of such values.
JMWE shows an error message on the issue view if any error occurs during the execution of the post-function. This message is displayed only if the current user is a Jira administrator.
Set only if property is empty: Sets the value of the selected property only if the property is empty.
Ignore empty value: Will not set (clear) the selected property, if the value is empty or null.