fix: Don't silently skip null assignment to OpenApiDocument.Tags

[baywet]

port of #2916 to v2

[github-code-quality]

Code Coverage Overview

Languages: C#

C# / code-coverage/dotnet

The overall coverage in the fix/null-tags-to-v2 branch is 41%. The coverage in the support/v2 branch is 88%.

Show a code coverage summary of the most impacted files.

File	support/v2 3764142	fix/null-tags-to-v2 06e2aba	+/-
/home/runner/wo...MapParameter.cs	100%	0%	-100%
/home/runner/wo...Deserializer.cs	81%	0%	-81%
/home/runner/wo...pyReferences.cs	63%	31%	-32%
/home/runner/wo...piJsonReader.cs	100%	72%	-28%
/home/runner/wo...Deserializer.cs	90%	62%	-28%
/home/runner/wo...s/OpenApiTag.cs	100%	76%	-24%
/home/runner/wo...Deserializer.cs	100%	81%	-19%
/home/runner/wo...Deserializer.cs	96%	81%	-15%
/home/runner/wo...Deserializer.cs	97%	89%	-8%
/home/runner/wo...piComponents.cs	94%	87%	-7%

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud