feat: support `--labels` on `helm install` and `helm upgrade`

[JonathanCrt]

Background

Helm 3.14 added -l, --labels stringToString on helm install and helm upgrade. Labels are attached to the release record (and copied onto the Secret/ConfigMap storing release state), useful for filtering and for org/billing tagging.

Helm SDK exposes this as (*action.Install).Labels map[string]string and (*action.Upgrade).Labels map[string]string (install.go:101).

Acceptance criteria

• InstallCommand.withLabel(String key, String value) adds a single label; multiple calls accumulate
• Same on UpgradeCommand (helm 3.14+ supports it there too)
• Labels reach the underlying helm Release record (verifiable in the storage Secret)
• Integration test confirms install/upgrade succeeds with labels and surfaces no errors

Proposed Java API

helm.install()
    .withName("r")
    .withLabel("env", "prod")
    .withLabel("team", "platform")
    .withKubeConfig(kc)
    .call();

Implementation guide

The codebase already passes Map<String,String> over JNA as a URL-encoded string. Copy this pattern for labels — see how Values flows.

Java side (InstallCommand.java, UpgradeCommand.java)

• Add private final Map<String,String> labels = new LinkedHashMap<>(); field.
• Add withLabel(String key, String value) (append into the map; return this).
• In call(), pass urlEncode(labels) as the new labels argument (helper already exists in HelmCommand).

JNA (InstallOptions.java, UpgradeOptions.java)

• Add public String labels; field; update @Structure.FieldOrder (append at the end) and the constructor signature.

CGO bridge (native/main.go)

• Add char* labels; to struct InstallOptions and struct UpgradeOptions. The field order must match the Java @Structure.FieldOrder exactly.
• Pass through: Labels: C.GoString(options.labels).

Go (native/internal/helm/install.go, upgrade.go)

• Add Labels string field to the Go options struct (URL-encoded; decoded inside Install/Upgrade).
• Decode with url.ParseQuery(options.Labels) (same pattern as mergeValues in install.go:289 for Values).
• Convert url.Values → map[string]string (take the first value per key).
• Set client.Labels = ....

Tests

• Add to HelmKubernetesTest.Install and HelmKubernetesTest.Upgrade nested classes. Labels persist in the release Secret, so client-only mode won't exercise them — needs the real KinD container.
• Scenarios:
  • Install with a single label — no exception, release lands as deployed
  • Install with multiple labels — same
  • Upgrade adding a label to a release that had none — succeeds
• Optionally: fetch the release Secret with the Fabric8 / k8s client (already on the test classpath via Testcontainers/KinD) and assert the metadata.labels block contains the expected entries. If too heavy, omit and trust the SDK.

Contributor checklist

• Java 8 syntax only
• Apache 2.0 header
• @author Javadoc tag
• DCO sign-off
• make build-native && ./mvnw test -pl helm-java -Dtest=HelmKubernetesTest green

References

• Helm CLI install: https://helm.sh/docs/helm/helm_install/
• Helm CLI upgrade: https://helm.sh/docs/helm/helm_upgrade/
• Helm 3.14 release notes: https://github.com/helm/helm/releases/tag/v3.14.0
• Project workflow: AGENTS.md → Adding a new Helm command
• Pattern to copy: how Values is URL-encoded across JNA — InstallCommand.java:106 + install.go:289 (url.ParseQuery)