How to configure Performance Goal approvals to trigger an approval when only the goal is updated

Summary:

The requirement is to trigger an approval to the line manager when an already created goal is updated by the employee. But this also should not be triggered when creating a new goal by the employee.

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When the employee creates a performance goal the approval should not be triggered but when any attribute of the goal is updated, the approval should be triggered to the line manager of the employee.

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