🐛 Fix crd flattening for structType marker to not create duplicate entries for XMapType

[chrischdi]

Bug was introduced in #693.

As outlined in #693 (comment) , #693 introduced the bug that x-kubernetes-map-type may now get set twice and thus result in two entries in allOf.

This is because before #693 the marker at the type definition was simply ignored but now they got combined.

This PR fixes the flattening to handle this case for the structType marker.

A similar fix for the markers mapType, listType and listMapKey is not necessary because setting them where the type is referenced would result in an error anyway. Before #693 this was also the case, but since #693 it is possible to set them at the type definition.

[chrischdi]

cc @robbie-demuth : could you give this a try?

[sbueringer]

/cherry-pick release-0.9
/lgtm

[k8s-infra-cherrypick-robot]

@sbueringer: once the present PR merges, I will cherry-pick it on top of release-0.9 in a new PR and assign it to you.

In response to this:

/cherry-pick release-0.9
/lgtm

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[FillZpp]

/lgtm

[alvaroaleman]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: alvaroaleman, chrischdi

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[k8s-infra-cherrypick-robot]

@sbueringer: #697 failed to apply on top of branch "release-0.9":

Applying: Fix crd flattening for XMapType to not duplicate entries
Using index info to reconstruct a base tree...
M	pkg/crd/flatten.go
M	pkg/crd/testdata/testdata.kubebuilder.io_cronjobs.yaml
Falling back to patching base and 3-way merge...
Auto-merging pkg/crd/testdata/testdata.kubebuilder.io_cronjobs.yaml
Auto-merging pkg/crd/flatten.go
CONFLICT (content): Merge conflict in pkg/crd/flatten.go
error: Failed to merge in the changes.
hint: Use 'git am --show-current-patch=diff' to see the failed patch
Patch failed at 0001 Fix crd flattening for XMapType to not duplicate entries
When you have resolved this problem, run "git am --continue".
If you prefer to skip this patch, run "git am --skip" instead.
To restore the original branch and stop patching, run "git am --abort".

In response to this:

/cherry-pick release-0.9
/lgtm

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[sbueringer]

@chrischdi Can you please open a manual cherry-pick PR when you have some time? Thank you!