How to prevent epic from closing until issues in the epic are closed

Use cases:

How to hide the workflow transition on the issue view screen for the epic issue type until all the issues within the section issues in the epic are closed
How to hide the workflow transition on the issue view screen for the epic issue type based on the status of child issues using a JQL condition(JSU)
How to hide the workflow transition on the issue view screen for the epic issue type based on the resolution of child issues using a JQL condition(JSU)

Instructions

Add the below steps on the Done transition to prevent epic from being closed until all the issues in the epic are closed.

Edit the workflow that is associated with target project.
Select the Done transition.
Select the Conditions tab and click Add condition
Select the JQL Condition(JSU) and click Add
Add the JQL Expression within the field as shown below:

"Epic Link" = {issue.key} AND status != Done

The JQL expression can be used based on the number of statuses. It means., if you have more than one status that are referring to issue closure, the JQL expression can be written as mentioned below:
"Epic Link" = {issue.key} AND status not in (Done, Completed, Resolved)
Tick the Must not find issues checkbox option to validate the results against the JQL.
Alternatively, this use case can configured with the resolution field but only when the proper resolution is set for the issue. Use the JQL Expression as shown below:
"Epic Link" = {issue.key} AND resolution is EMPTY
Publish the workflow.
In order to test this scenario:
1. Create an epic and add issues to it.
2. Transit the epic and check if the Done transition is visible on the issue screen or not, when the issues within the epic are not closed.
3. Now, transit all the issues in epic to close it and check whether the Done transition on the epic is appearing.