Validating Goals Measurement to be Mandatory

Summary:

We need to validate the Measurement section to be mandatory.

Content (required):

While creating Employee Goals we need to force him to add a Goal Measurement, I've tried to loop on the Measurement lines to find the Measurement lines it fires but the event fires all the time before adding a new line.

Please advise if there is any way to validate this section.

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Code Snippet (add any code snippets that support your topic, if applicable):