jsonMergePatch operations use Fabric8 JSON Patch semantics and can remove spec #3512

What happened?

ResourceOperations.jsonMergePatch(...) and ResourceOperations.jsonMergePatchPrimary(...) are documented as applying RFC 7386 JSON Merge Patch, but they delegate to Fabric8's no-context .patch() method.

Fabric8's default .patch() intentionally fetches the current resource and computes an RFC 6902 JSON Patch diff. When the supplied resource is a partial metadata patch, the generated diff removes fields that are omitted from the partial object, including spec.

The status variants are not affected because Fabric8's patchStatus() explicitly selects PatchType.JSON_MERGE.

Versions verified

• Java Operator SDK 5.3.5 with Fabric8 7.7.0
• Java Operator SDK 5.5.0 with Fabric8 7.8.0

The behavior is still present in the current main branch.

Minimal reproduction

Assume this custom resource already exists:

apiVersion: example.io/v1
kind: Example
metadata:
  name: example
spec:
  value: keep-me

Apply a partial metadata patch through ResourceOperations:

Example patch = new Example();
patch.getMetadata().setName("example");
patch.getMetadata().setLabels(Map.of("resolved", "true"));

context.resourceOperations().jsonMergePatchPrimary(patch);

Fabric8 computes a JSON Patch equivalent to:

[
  {"op":"add","path":"/metadata/labels/resolved","value":"true"},
  {"op":"remove","path":"/spec"},
  {"op":"remove","path":"/status"}
]

For a CRD whose root spec is optional, the API server accepts the patch and permanently removes the spec. We encountered this in a real controller where subsequent reconciliation failed because getSpec() returned null.

Expected behavior

Methods named and documented as JSON Merge Patch should send application/merge-patch+json and preserve fields omitted from the partial resource.

Relevant implementation

JOSDK 5.5.0 delegates to .patch() without specifying a patch type:

• ResourceOperations.jsonMergePatchPrimary

Fabric8's default .patch() selects JSON Patch and diffs the current and supplied resources:

• HasMetadataOperation.patch()
• OperationSupport.handlePatch(...)

Suggested fix

Make the non-status JSON Merge Patch operations pass an explicit patch context, for example:

r -> context.getClient()
    .resource(r)
    .patch(PatchContext.of(PatchType.JSON_MERGE), r)

The cache and own-event filtering behavior can remain unchanged. Regression coverage should create a complete resource, apply a partial metadata merge patch, and assert that spec survives.