Enable optionalfields linter

Author: sbueringer

.golangci-kal.yml

@@ -23,6 +23,8 @@ linters:
               - "nobools" # Bools do not evolve over time, should use enums instead.
               - "nofloats" # Ensure floats are not used.
               - "nomaps" # Ensure maps are not used.
+              - "optionalfields" # Ensure that all fields marked as optional adhere to being pointers and
+                                 # having the `omitempty` value in their `json` tag where appropriate.
               - "optionalorrequired" # Every field should be marked as `+optional` or `+required`.
               - "requiredfields" # Required fields should not be pointers, and should not have `omitempty`.
               - "statusoptional" # Ensure all first children within status should be optional.
@@ -46,6 +48,12 @@ linters:
           # optionalOrRequired:
           #   preferredOptionalMarker: optional | kubebuilder:validation:Optional # The preferred optional marker to use, fixes will suggest to use this marker. Defaults to `optional`.
           #   preferredRequiredMarker: required | kubebuilder:validation:Required # The preferred required marker to use, fixes will suggest to use this marker. Defaults to `required`.
+            optionalFields:
+              pointers:
+                preference: Always # Always | WhenRequired # Whether to always require pointers, or only when required. Defaults to `Always`.
+                policy: SuggestFix # SuggestFix | Warn # The policy for pointers in optional fields. Defaults to `SuggestFix`.
+              omitempty:
+                policy: SuggestFix # SuggestFix | Warn | Ignore # The policy for omitempty in optional fields. Defaults to `SuggestFix`.
           # requiredFields:
           #   pointerPolicy: Warn | SuggestFix # Defaults to `SuggestFix`. We want our required fields to not be pointers.
 
@@ -70,6 +78,10 @@ linters:
       text: "Conditions field must be a slice of metav1.Condition"
       linters:
         - kubeapilinter
+    - path: "api/addons/v1beta1/*|api/bootstrap/kubeadm/v1beta1/*|api/controlplane/kubeadm/v1beta1/*|api/core/v1beta1/*|api/ipam/v1beta1/*|api/ipam/v1alpha1/*|api/runtime/v1alpha1/*"
+      text: "optionalfields"
+      linters:
+        - kubeapilinter
     - path: "api/core/v1beta2/*|api/core/v1beta1/*"
       text: "field Conditions type Conditions must have a maximum items, add kubebuilder:validation:MaxItems marker"
       linters:

hack/tools/.custom-gcl.yaml

@@ -3,4 +3,4 @@ name: golangci-lint-kube-api-linter
 destination: ./bin
 plugins:
 - module: 'sigs.k8s.io/kube-api-linter'
-  version: v0.0.0-20250605073038-74075c8eae51
+  version: v0.0.0-20250613105907-bce00ef0e9a6