In this example opening and closing is done by the client.
The attribute
omit="true"
set for the 'show'-button and the 'hide'-button to prevent submitting.
For the section
collapsedMode="hidden"
is set.
After the 'hide' transition, the content of the section will be in the 'hidden' state.
The hidden content of the section will also be validated.
If the 'Submit'-button is pressed while the input field is empty, a violation occurs.