Out of Sync on Argo CD Server Side Apply for existing resource.

[iam-veeramalla]

Checklist:

• I've searched in the docs and FAQ for my answer: https://bit.ly/argocd-faq.
• I've included steps to reproduce the bug.
• I've pasted the output of argocd version.

Describe the bug
I was testing the Argo CD Server Side Apply feature by building Argo CD from master.

I used the Argo CD SSA on an existing resource on the cluster and noticed that Argo CD was able to apply the configuration using serverside but the application stays out-of-sync.

The same configuration is well synced without ServerSideApply.

To Reproduce

1. Build Argo CD from master or use the Argo CD Image below.
   docker.io/abhishekf5/argocd:testing-ssa:sha256:ac5d7b74e71eb6453944d564e1b5f056a4f3d8c4447141cde0e9f540a7115afc
2. Create a simple nginx resource on your namespace WITHOUT Argo CD.
   kubectl create deploy nginx --image=nginx
   and label the resource
   kubectl label deploy nginx foo1=bar1 foo2=bar2
3. Create an Argo CD application which points to the nginx deployment yaml. You can use the application yaml as shown below.

apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
  name: test
  namespace: default
spec:
  destination:
    namespace: default
    server: https://kubernetes.default.svc
  project: default
  source:
    path: ssa
    repoURL: https://github.com/iam-veeramalla/demo-repo
    targetRevision: HEAD
  syncPolicy:
    syncOptions:
    - ServerSideApply=true

Please refer to the screenshots section for more information.

Expected behavior
Application should not be out-of-sync.

Screenshots

[ashutosh16]

Fix is proposed in the gitops-engine PR : gitops-engine/pull/467. Similar issue is report earlier in argo-cd/issues/10627

[iam-veeramalla]

Thanks @ashutosh16

[leoluz]

@iam-veeramalla tks for the detailed issue.
I am closing it as this bug is already being tracked in: #10627
It would be great if you could give it a try once we merge the gitops-engine PR and update Argo CD master with it.