[BEAM-7013] Update BigQueryHllSketchCompatibilityIT to cover empty sketch cases

[robinyqiu]

r: @zfraa

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Post-Commit Tests Status (on master branch)

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Java
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Pre-Commit Tests Status (on master branch)

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[robinyqiu]

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[robinyqiu]

See all the 4 test cases pass here: https://builds.apache.org/job/beam_PostCommit_Java_PR/237/testReport/org.apache.beam.sdk.extensions.zetasketch/BigQueryHllSketchCompatibilityIT/

[zfraa]

Really nice that you got this to work and that it's now available to folks as an example how to do this!
Main question is double-checking that this is testing what we think it is testing.
Beyond this PR, we should make sure that this gets covered in a pattern. But also: is there any way we could make the conversion functors (parseQueryResultToByteArray, and the inlined one for the other direction) available to users as utility objects or methods? It seems suboptimal if every person who wants to have Beam and BQ interoperate on HLL++ would need to copy out the code from a pattern. E.g., if there's ever a new edge case to be handled in this conversion, it's easier to update that centrally.

[robinyqiu]

is there any way we could make the conversion functors (parseQueryResultToByteArray, and the inlined one for the other direction) available to users as utility objects or methods?

I have considered this but unfortunately we cannot do that, because in the same function users might want to parse other fields. However I do find a way to extract part of the logic into its own function. See the getSketchFromByteBuffer function.

[zfraa]

Yay, thank you for adding the utility function to HllCount.java! It's a pity we can't do it for both directions...

[robinyqiu]

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[robinyqiu]

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[robinyqiu]

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