Native Image Test

[crazyrokr]

Summary

Removes the javaagent-generated reachability-metadata.json from the GraalVM native build and replaces its coverage with declarative Spring AOT hints, library-supplied metadata, build flags, and a reflection-free enum lookup — so the native image ships with no project-maintained reachability-metadata.json and no RuntimeHintsRegistrar. Also adds an automated test that boots the native binary and runs the existing MQTT integration specs against it.

Changes

• Declarative hints for rlib array types. rlib's Array/ArrayFactory collections create typed arrays via Array.newInstance, so each component's array class must still be registered. NativeReflectionHintsConfig (a @Configuration imported by MqttBrokerApplication) declares these via @RegisterReflectionForBinding — an AOT-processed annotation, not a JSON file or RuntimeHintsRegistrar. (ExpirableSession/NotExpirableSession were made public so their array classes are referenceable.)
• Third-party + JCE coverage via standard mechanisms. Enabled the GraalVM Reachability Metadata Repository (metadataRepository { enabled = true }) for libraries that don't ship their own metadata (Jackson, Logback, PostgreSQL-JDBC, SnakeYAML; Flyway 11.19.0 via the repo's latest-config fallback), and --enable-all-security-services for the JCE/TLS providers that were the 51 com.sun.crypto.provider entries. The GraalVM vendor match was broadened from GraalVM Community to GraalVM (matches CE and Oracle).
• Automated native verification. NativeImageVerificationTest launches the compiled native binary, waits for the Started external MQTT network marker, and re-runs the application's integration specs against it via JUnit Platform TestKit (EmbeddedSpecRunner). Wired as the nativeImageTest task, with copyNativeImageTestResources staging test config/credentials/ACL next to the binary. Supporting changes: application exposes its test fixtures (testFixturesImplementation) and junit-platform-testkit was added.

Notes

• --enable-all-security-services is deprecated by GraalVM but functional; a follow-up can migrate to its successor.
• Flyway 11.19.0 relies on the metadata repository's latest-config fallback; if a future migration hits untested Flyway behavior, pin it via metadataRepository { moduleToConfigVersion = ['org.flywaydb:flyway-core': '11.14.1'] }.