Validator Feature - Empty Timers Check

[MichielOda]

Throw a certain error when Protocol/Timers/Timer/Content is empty.

Extra info:

• Timer threads
• Content element

<Timers>
	<Timer id="1">
		<Name>Fast Timer (10s)</Name>
		<Time initial="true">10000</Time>
		<Interval>75</Interval>
		<Content>
		</Content>
	</Timer>
	<Timer id="2">
		<Name>Medium Timer (1m)</Name>
		<Time initial="true" dataDisplay="30000">60000</Time>
		<Interval>75</Interval>
		<Content>
		</Content>
	</Timer>
	<Timer id="3">
		<Name>Slow Timer (1h)</Name>
		<Time initial="true">3600000</Time>
		<Interval>75</Interval>
		<Content>
		</Content>
	</Timer>
</Timers>

If this feature is developed, merged, and released, the assignee will be granted 750 DevOps points.
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