Set policy tags to empty instead of null

[tabdulradi]

Currently when BigQuery returns policy tag object without names, the whole policy tag field is set to null, which is not consistent with the REST Api, this pull request changes the behaviour to return an instance with names set to null instead.

This change modifies a previous PR #522, that was created in response to my GCP support ticket, slightly tweaking the behaviour to make it more consistent with the REST api.

• Make sure to open an issue as a bug/issue before writing your code! There is GCP issue instead. The case Id is 24194276
• Ensure the tests and linter pass
• Code coverage does not decrease (if any source code was changed)
• Appropriate docs were updated (if necessary)

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[codecov]

Codecov Report

Merging #545 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #545   +/-   ##
=========================================
  Coverage     81.49%   81.49%           
  Complexity     1226     1226           
=========================================
  Files            77       77           
  Lines          6220     6221    +1     
  Branches        691      691           
=========================================
+ Hits           5069     5070    +1     
  Misses          792      792           
  Partials        359      359           

Impacted Files	Coverage Δ	Complexity Δ
...ain/java/com/google/cloud/bigquery/PolicyTags.java	100.00% <100.00%> (ø)	6.00 <2.00> (ø)

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[tabdulradi]

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[shollyman]

Thanks for the submission. However, the backend service response is also being corrected so that it doesn't provide the empty message for policyTags, which is the behavior the first PR mirrors. In this case, I'm going to recommend that we don't move forward with this PR.

[stephaniewang526]

closing per @shollyman comment

[marengaz]

@shollyman @stephaniewang526

the reason for suggesting this change was so that we can tell the difference between the following scenarios:

• policy tag was never added to this field "policyTags":null
• policy tag was added to this field "policyTags":{"names":["projects/myproj/locations/eu/taxonomies/123/policyTags/456"]}
• policy tag was added to this field, then removed "policyTags":{"names":[]}

it mirrors the behaviour of the description field:

• description was never added to this field "description":null
• description was added to this field "description":"my description"
• description was added to this field, then removed "description":""

we value this granularity. whats the reason for removing it?

[shollyman]

If you want awareness of this kind of change, then I'd suggest something like the BigQuery audit log feature. If it doesn't convey the information you need, then I'd suggest making a request on the public issue tracker or via support channels.