An end state may optionally be configured with the name of a view to render
when entered. This view will be rendered if the end state terminates the
entire flow execution as a kind of flow ending "confirmation page".
Note: if no viewName property is specified and this
end state terminates the entire flow execution, it is expected that some
action has already written the response (or else a blank response will
result). On the other hand, if no viewName is specified and
this end state relinquishes control back to a parent flow, view rendering
responsibility falls on the parent flow.