NIFI-7488 Listening Port property on HandleHttpRequest is not validated when Variable registry is used

[adarmiento]

Description of PR

HandleHttpRequest.PORT is validated

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[MikeThomsen]

Why are you doing this? Is the addValidator call not validating items from the variable registry?

[adarmiento]

I made a unit test using invalid values (passing from the registry), calling the .assertValid() was not marking the processor as invalid

[pvillard31]

The validators, most of the time, won't do anything if expression language is used to configure the property. I guess we could improve the validators based on the EL scope of the property: if the scope is Variable Registry, we should be able to validate the property even if EL is used.

[github-actions]

We're marking this PR as stale due to lack of updates in the past few months. If after another couple of weeks the stale label has not been removed this PR will be closed. This stale marker and eventual auto close does not indicate a judgement of the PR just lack of reviewer bandwidth and helps us keep the PR queue more manageable. If you would like this PR re-opened you can do so and a committer can remove the stale tag. Or you can open a new PR. Try to help review other PRs to increase PR review bandwidth which in turn helps yours.