[ISSUE apache/dubbo#13862] Migrate dubbo-samples-triple-rest-openapi-generator to Spring Boot 3.2.3

[zeng-bohan]

Migrates the last remaining Spring Boot 2 sample to Boot 3, as tracked in apache/dubbo#13862 (claim comment: apache/dubbo#13862 (comment)).

Note: this supersedes #1300, which was auto-closed when the fork head repository was briefly deleted. The changes are identical (branch re-pushed, head commit fd73f93).

Changes

• Bump spring-boot-starter-parent from 2.7.18 to 3.2.3 in dubbo-samples-triple-rest-openapi-generator, aligning the module with the dubbo-samples-triple-rest aggregate parent BOM — this was the last sample in the repository still on Spring Boot 2.x
• Replace javax.annotation-api with jakarta.annotation-api and migrate the generated sources from javax.annotation.Generated to jakarta.annotation.Generated
• Enable useJakartaEe in the pom-generator.xml openapi-generator config (7.16.0 supports it) so future regenerations stay on the jakarta namespace
• Update README system requirements: Java 8+ → Java 17+

Verification

• mvn clean package -DskipTests succeeds on JDK 17 (same command as the CI build opts, which also test against spring-boot.version:3.2.3)
• No javax imports remain under src/

Notes

• The contextLoads test requires a running Zookeeper and is skipped by CI's -DskipTests build opts, so it is not affected by this change.

[zeng-bohan]

Friendly bump after two weeks: this migrates the last remaining Spring Boot 2 sample in dubbo-samples-triple-rest to Boot 3 / JDK 17, as tracked in apache/dubbo#13862, and CI is green. It supersedes #1300 (closed in favour of this one). Would appreciate a review when someone has a moment — happy to split or adjust the scope if that makes it easier to land. Thanks!

[zeng-bohan]

Closing this for now: I've hit the per-user open pull request limit on my account and need the slot for a higher-priority change. The branch stays available on my fork, and I'm happy to reopen this once a slot frees up. Thanks!

[zeng-bohan]

The Integration Test (Java17, Job3) failure in run 34734122523 is infrastructure, not the change: the job died 48 seconds in, while composing the test environment, because Docker Hub's auth endpoint returned a 502 while pulling the mysql:5.7.40 base image:

ERROR: failed to build: failed to solve: mysql:5.7.40: failed to resolve source metadata for docker.io/library/mysql:5.7.40:
failed to authorize: failed to fetch oauth token: unexpected status from POST request to https://auth.docker.io/token: 502 Bad Gateway

Up to that point the shard was green (BUILD SUCCESS for the test runner). Two corroborating points that this is a Docker Hub-side flake rather than the migration:

• the same Java17, Job3 shard passed in the parallel run for the other Dubbo version minutes later (run 34734122556), and every other mysql-backed shard (Java8/Java11/Java21 Job3) passed here too;
• the failure happens during the docker-compose env setup, before any test of this PR's module runs.

Could someone with write access re-run the failed job? Happy to push a trivial retrigger instead if that's easier for the workflow.