Allow factory files to be empty

[LucaPrete]

Allow net-vpc-firewall factory files to be empty.

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Checklist

I applicable, I acknowledge that I have:

• Read the contributing guide
• Ran terraform fmt on all modified files
• Regenerated the relevant README.md files using tools/tfdoc.py
• Made sure all relevant tests pass

[ludoo]

hmmmmmm :)

[ludoo]

@wiktorn @juliocc I don't see anything against doing this here, WDYT?

[wiktorn]

@wiktorn @juliocc I don't see anything against doing this here, WDYT?

If I read the code correctly, it solves the problem when egress or ingress is null in YAML, but not when the file is empty?

Gave it a shot with patch:

[LucaPrete]

Good point. I can add the coalesce also above.

[LucaPrete]

@wiktorn I added some code which should protect against both cases. Please, let me know if the test now works.

[wiktorn]

Works for those two cases:

configs/firewall/rules/rule1.yaml:

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configs/firewall/rules/rule2.yaml:

---

ingress: {}
egress: null

[juliocc]

LGTM