fix: do not eagerly evaluate the cluster-scoped fallback in KubernetesResourceFetcher

[csviri]

fetchResource selected between a namespaced and a cluster-scoped lookup
with Optional.orElse:

return resourceId.getNamespace()
    .map(ns -> client.resources(rClass).inNamespace(ns).withName(name).get())
    .orElse(client.resources(rClass).withName(name).get());

orElse evaluates its argument unconditionally, so every namespaced
lookup also performed the cluster-scoped GET. For a namespaced resource
type that second request either queries whichever namespace the client
happens to default to or fails outright, and its result is then thrown
away.

This runs on the BoundedItemStore cache-miss path
(refreshMissingStateFromServer), so it doubles the API server requests
for every bounded-cache refresh of a namespaced resource.

Switches to orElseGet so the fallback is only evaluated for
cluster-scoped resource ids.

Part of #3517

[Copilot]

Pull request overview

This PR updates KubernetesResourceFetcher in operator-framework-core to avoid eagerly executing a cluster-scoped fallback lookup when fetching resources, reducing unnecessary Kubernetes API calls on the bounded-cache refresh path.

Changes:

• Replaces Optional.orElse(...) with Optional.orElseGet(...) so the fallback GET is evaluated lazily.
• Keeps the existing namespaced-vs-cluster-scoped selection logic based on presence of a namespace in the ResourceID.

Comments suppressed due to low confidence (1)

operator-framework-core/src/main/java/io/javaoperatorsdk/operator/processing/event/source/cache/KubernetesResourceFetcher.java:48

• Optional.map(...) becomes empty when the mapper returns null (it wraps via ofNullable). That means if the resource ID is namespaced but the namespaced GET returns null (resource deleted / not found), this code will still execute the fallback cluster-scoped/default-namespace GET and may return/cache the wrong resource under the namespaced key. The fallback should only run when the namespace is absent, not when a namespaced lookup returns null.

    return resourceId
        .getNamespace()
        .map(ns -> client.resources(rClass).inNamespace(ns).withName(resourceId.getName()).get())
        .orElseGet(() -> client.resources(rClass).withName(resourceId.getName()).get());