NIFI-5230: Fixed NPE in InvokeScriptedProcessor on customValidate

[mattyb149]

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[MikeThomsen]

+1 LGTM. Running the scripting bundle tests now with contrib-check before merging.

[ottobackwards]

Couple of questions, if I may ask.

[ottobackwards]

Why are we using HashSet here, when we initialize to ArrayList initially? Shouldn't they be the same and consistent?

[ottobackwards]

Also, I don't understand customValidate. The validationResults are used to 'seed' the currentValidationResults, but if empty, any new validation results are not set back to validationResults. Is that right?

[bdesert]

@ottobackwards , when a processor is invalid (customValidate returned validation errors), we keep all the validationResults. Method 'customValidate' just check if there are already errors - no need to validate again, just return whatever is stored.
When any property is getting modified - these validation results may not be accurate anymore, so we have to reset them. Once reset (onPropertyModified), next call to customValidate will run full validation and set new errors if found. So at any point we don't drop validation results for no reason. Am I missing anything?

[ottobackwards]

Ok, that makes sense. Thanks for the explanation.

[bdesert]

@ottobackwards , regarding Set vs List. Validation Result supposed to be Collection, so technically - any of them can be used. But consistency should come with Set, as if you check super class AbstractConfigurableComponent, its customValidate returns:
return Collections.emptySet();
So, I would say, we need to refactor ArrayList into Set, but then there will be more potential regression impact. I'd recommend to keep it as is for this PR/Jira, and have another ticket opened on cosmetic improvement to change ArrayList to to some Set implementation during initialization. I hope it makes sense.