Make geom_exposure optional in MapDatasetOnOff.from_geoms

[AtreyeeS]

This addresses #4490

[codecov]

Codecov Report

Merging #4593 (8ce693b) into main (cc3d847) will not change coverage.
The diff coverage is n/a.

❗ Current head 8ce693b differs from pull request most recent head 70fd481. Consider uploading reports for the commit 70fd481 to get more accurate results

@@           Coverage Diff           @@
##             main    #4593   +/-   ##
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  Coverage   95.05%   95.05%           
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  Files         221      221           
  Lines       31517    31517           
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  Hits        29959    29959           
  Misses       1558     1558           

Impacted Files	Coverage Δ
gammapy/datasets/map.py	93.94% <ø> (ø)

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[registerrier]

Thanks @AtreyeeS . This looks good. See small inline comments.

[registerrier]

Thanks @AtreyeeS . No further comment from my side.

[registerrier]

CI fail is unrelated. Merging.

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout v1.0.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 9f510bda5802e8df571479a9b33df94337d456ba

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #4593: Make geom_exposure optional in MapDatasetOnOff.from_geoms'

4. Push to a named branch:

git push YOURFORK v1.0.x:auto-backport-of-pr-4593-on-v1.0.x

5. Create a PR against branch v1.0.x, I would have named this PR:

"Backport PR #4593 on branch v1.0.x (Make geom_exposure optional in MapDatasetOnOff.from_geoms)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.