Jira allows you to perform additional tasks as part of a workflow transition through the use of post functions. Jira makes heavy use of post functions internally; for example, in the case of an out-of-the-box workflow, the resolution field value is cleared automatically when you reopen an issue.

In this recipe, we will look at how to add post functions to a workflow transition. We will add a post function to automatically clear out the value stored in a Reason for Freezing custom field when we take it out of the Frozen status.