NIFI-14141 Accept Expression Language statement in GenerateFlowFile, …

[markobean]

…File Size property allowing FlowFiles of variable sizes to be generated. Included some examples of EL statements in Additional Details for GenerateFlowFile.

Summary

NIFI-14141

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[exceptionfactory]

Thanks for putting forward the expression language-based approach @markobean.

I noted a couple things on the validator configuration, and I also recommend simplifying the unit test to avoid using the random() function. The Additional Details documentation is great, and provides very useful examples, but it isn't necessary to introduce that complexity in the unit test because it is a feature of expression language itself.

[exceptionfactory]

Thanks for making the updates @markobean, the simplified unit test approach looks good.

I tested reverting the validator changes and the DATA_SIZE_VALIDATOR works with and without EL configured in the property, based on the unit tests included. Please review that behavior as it should be possible to revert that change. If you are still seeing an error, there could be something else going on.

[exceptionfactory]

Thanks for working through the feedback @markobean, the latest version looks good! +1 merging