[Backport release-1.10] Fix EKS Cluster conversion by injecting index key when list

[turkenh]

Note

Backport of #1669 to provider-aws-release-1.10.

Description of your changes

Fixes the issue described in crossplane/upjet#465

We have observed some issue with the EKS Cluster resource where when we apply the manifest and let it to resolve references to spec.forProvider.vpcConfig.securityGroupIds, we noticed the following error in the status:

  - lastTransitionTime: "2025-02-06T07:28:46Z"
    message: 'cannot patch the managed resource via server-side apply: Cluster.eks.aws.upbound.io
      "some-eks-cluster" is invalid: [spec.forProvider.vpcConfig: Invalid
      value: "null": spec.forProvider.vpcConfig in body must be of type array: "null",
      <nil>: Invalid value: "null": some validation rules were not checked because
      the object was invalid; correct the existing errors to complete validation]'
    reason: ReconcileError
    status: "False"
    type: Synced

Our assumption (which is validated by observing this changes fixes the problem) is as follows:

Server Side Apply uses merge strategies to make decisions during merging changes by various owners/managers. In EKS Cluster object, for vpcConfig field, we mark +listType as map and //+listMapKey as index. During conversion between v1beta1 to v1beta2, we convert the that field from array to object, losing the index field since it is not in the schema. This is fine in most cases since in v1beta1 of the object schema index defaults to "0" , even though you don’t provide it.

However, with Server Side Apply, apparently some on the fly conversions happening when different managers using different api versions and losing index field causing unexpected merging results and drop of the whole spec.forProvider.vpcConfig object.

I have:

• Read and followed Crossplane's contribution process.
• Run make reviewable to ensure this PR is ready for review.
• Added backport release-x.y labels to auto-backport this PR if necessary.

How has this code been tested

Please see crossplane/upjet#465

[turkenh]

/test-examples="examples/eks/v1beta2/cluster.yaml"

[turkenh]

/test-examples="examples/s3/v1beta1/bucket.yaml"

[turkenf]

Thank you @turkenh, LGTM.