Support Elasticsearch 9.x as storage

[kezhenxu94]

Fix the issue

Adds support for running SkyWalking OAP against Elasticsearch 9.x as storage.

Why

The in-tree ES client (library-elasticsearch-client) selects its request factory / codec per server version in ElasticSearchVersion. The ceiling was major == 8, so any server reporting major version 9 fell through to UnsupportedOperationException("Unsupported version") and OAP refused to start against an Elasticsearch 9 cluster.

ES 9 keeps the same REST surface the ES 8 path already relies on — typeless document writes (POST /{index}/_update/{id}) and composable index templates (PUT /_index_template/{name}) — so no new factory or codec is needed; the version gate just needs to admit major >= 8. This mirrors how OpenSearch is already handled version-agnostically.

What changed

• ElasticSearchVersion: if (major == 8) → if (major >= 8) for the ElasticSearch distribution (8.x, 9.x and later use the existing typeless-doc + composable-template path).
• ElasticSearchIT: add an ElasticSearch 9.3.0 parameter (all IT methods run against a real ES 9 container).
• CI skywalking.yaml: add a Storage ES 9.3.0 e2e case alongside the existing 8.18.8.
• Docs: storage doc supported-versions line now lists ElasticSearch 9.x; changelog entry added.

Verified locally against a real elasticsearch:9.3.0 container: version detection, composable index template, typeless index/get/update/delete, and search all behave as expected.

• Update the CHANGES log.

[Copilot]

Pull request overview

This pull request extends SkyWalking OAP’s in-tree Elasticsearch client/version gating so the existing Elasticsearch 8.x request/codec path is also used for Elasticsearch 9.x, and expands CI/IT coverage plus docs/changelog accordingly.

Changes:

• Update ElasticSearchVersion to treat Elasticsearch major versions >= 8 as supported (reusing the existing typeless-doc + composable-template request path).
• Add an Elasticsearch 9.x integration-test parameter and a new CI e2e workflow case for Elasticsearch 9.x.
• Document Elasticsearch 9.x support and add a changelog entry.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
oap-server/server-library/library-elasticsearch-client/src/test/java/org/apache/skywalking/library/elasticsearch/ElasticSearchIT.java	Adds an Elasticsearch 9.x Testcontainers parameter to run the existing IT suite against ES 9.
oap-server/server-library/library-elasticsearch-client/src/main/java/org/apache/skywalking/library/elasticsearch/ElasticSearchVersion.java	Broadens the Elasticsearch version gate to allow 9.x (and later) to use the existing 8.x request/codec implementation.
docs/en/setup/backend/storages/elasticsearch.md	Updates the supported versions list to include Elasticsearch 9.x.
docs/en/changes/changes.md	Adds a changelog bullet announcing Elasticsearch 9.x storage support.
.github/workflows/skywalking.yaml	Adds an e2e CI matrix entry to run the ES storage case against a 9.x tag.

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