Description

We are now two LTS releases behind in our Java support. Given that we are currently on Java 17 and LTS Java versions are 17, 21, and 25, we should move swatch-core and swatch-core-test up to Java 21.

The example and proof of concept for upgrading specific maven modules to use Java 21 was done as part of SWATCH-4144. The PR for that work can be found here: https://github.com/RedHatInsights/rhsm-subscriptions/pull/5122/files

These modules form the core infrastructure layer that multiple service modules depend on. swatch-core provides shared business logic and data access patterns, while swatch-core-test provides shared test utilities. These modules must be upgraded before the service modules that depend on them (such as swatch-tally, swatch-system-conduit, swatch-contracts, and swatch-billable-usage).

Note: This upgrade targets Java 21, not Java 25, because a UBI image for OpenJDK 25 is not yet available.

Acceptance Criteria

• The swatch-core module's POM is updated to Java 21.

• The swatch-core-test module's POM is updated to Java 21.

• Both modules compile, run, and pass all tests with OpenJDK 21.

• Any container images for these modules (if applicable) are updated to use ubi9/openjdk-21 as the base image.

Out of scope:

• Other modules and services and the parent pom