NIFI-5083: enabled EL support for processor configuration of Kafka consumer group id

[snagafritz]

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I started to write unit tests for these changes then realized that the tests were really verifying the evaluation of the EL expressions, and I assume far better unit tests for this already exist. I will attach a video of me verifying expected behavior of a build of this branch to the JIRA ticket.

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[bbende]

I think you will also need to find where the group id property is used and ensure that evaluateAttributeExpressions() is called when obtaining the value.

[bbende]

Actually, I take back my last comment, I now see where the value is obtained and it does have the logic:

String propertyValue = propertyDescriptor.isExpressionLanguageSupported()
                    ? context.getProperty(propertyDescriptor).evaluateAttributeExpressions().getValue()
                    : context.getProperty(propertyDescriptor).getValue();

Sorry about that.

[zenfenan]

Reviewing..

[zenfenan]

+1 LGTM. Merged to master. Thanks @snagafritz

[zenfenan]

@snagafritz Hey.. I forgot to close this PR while merging. It is now merged to the master. Can you manually close this PR?