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For information on where the post-function needs to be placed on a transition, see Placing post-functions on a transition.
When you add this post-function to a transition and trigger the transition, the add-on checks for the default member of the selected Project Role. If such member is found, it assigns the issue to the fetched user. If not, the issue is assigned to a random member of the selected Project Role. If there are multiple default members, a random member is picked among them.
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