We need the go struct tags `patchMergeKey` and `patchStrategy`
for fields that support a strategic merge patch. For native
resources, we can easily figure out these tags since we know
the fields.
Because custom resources are decoded as Unstructured and
because we're missing the metadata about how to handle
each field in a strategic merge patch, we can't find the
go struct tags. Hence, we can't easily do a strategic merge
for custom resources.
So we should fail fast and return an error.
Kubernetes-commit: 79349c93bddcc1125a9d6ea4528c6d63b172f083
Add interpretPatchError to return appropriate http code
(400 or 422) according to the error type.
We add this function in apiserver because we don't want
to mention the http code in apimachinery. The apimachinery
code is also used in kubectl. The client should not return
a server error.
Add a test to validate the http error code and error message.
Kubernetes-commit: e0a2168ecbf8b4e43f932a32fa55cd55215123cc
Nikhita Raghunath