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For example, the Copy Value From Other Field Post - Function allows you to define the issue in transition as the source or destination of the copy operations, while you define the other end with an issue relation.
The field value will then be read from the source issue and be written to the destination issue.
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Copy Value From Other Field Post - Function: there should be only one source issue. Otherwise, it is not clear from which the value will be read. (The current implementation will just randomly pick one of them and ignore the rest.)
If you use Create a Linked Issue to create a new sub-task, you must also configure this post function to create the new issue as an issue type of a sub-task and make sure the target project is the same as the one of the issue in transition.
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