Details on add guest os optional

[DaanHoogland]

Description

This PR fixes a issue reported in the user mail list: https://lists.apache.org/thread/clsoyz3kgp47ppbhtqp8m0o2fkczqrmk

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

Feature/Enhancement Scale or Bug Severity

Feature/Enhancement Scale

• Major
• Minor

Bug Severity

• BLOCKER
• Critical
• Major
• Minor
• Trivial

Screenshots (if appropriate):

How Has This Been Tested?

[DaanHoogland]

@blueorangutan package

[blueorangutan]

@DaanHoogland a [SF] Jenkins job has been kicked to build packages. It will be bundled with KVM, XenServer and VMware SystemVM templates. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result [SF]: ✔️ el7 ✔️ el8 ✔️ el9 ✔️ debian ✔️ suse15. SL-JID 6650

[codecov]

Codecov Report

Merging #7812 (a2e5b1a) into 4.18 (c86684f) will decrease coverage by 0.01%.
The diff coverage is n/a.

@@             Coverage Diff              @@
##               4.18    #7812      +/-   ##
============================================
- Coverage     13.02%   13.02%   -0.01%     
+ Complexity     9031     9029       -2     
============================================
  Files          2720     2720              
  Lines        257010   257010              
  Branches      40083    40083              
============================================
- Hits          33472    33467       -5     
- Misses       219336   219342       +6     
+ Partials       4202     4201       -1     

see 1 file with indirect coverage changes

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[DaanHoogland]

I don't think this will be touched by any smoke tests

[BryanMLima]

LGTM, already manually tested this change with PR #6979.

[harikrishna-patnala]

code LGTM