App Config Spring - Snapshot references

[mrm9084]

Description

Adds support for Snapshot References

All SDK Contribution checklist:

• The pull request does not introduce [breaking changes]
• CHANGELOG is updated for new features, bug fixes or other significant changes.
• I have read the contribution guidelines.

General Guidelines and Best Practices

• Title of the pull request is clear and informative.
• There are a small number of commits, each of which have an informative message. This means that previously merged commits do not appear in the history of the PR. For more information on cleaning up the commits in your PR, see this page.

Testing Guidelines

• Pull request includes test coverage for the included changes.

[Copilot]

Pull request overview

This PR adds first-class support for Snapshot Reference settings in the Spring Cloud Azure App Configuration config module, including tracing/telemetry updates and tests to validate reference resolution and feature flag behavior when snapshots are involved.

Changes:

• Resolve snapshot reference settings by fetching the referenced snapshot and loading its settings as properties.
• Extend request correlation/tracing to include a new SnapshotRef feature tag.
• Update property source construction to pass a FeatureFlagClient, and add/adjust tests and changelog entry for the new behavior.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/AppConfigurationApplicationSettingPropertySource.java	Adds snapshot reference resolution and integrates feature flag processing for snapshot-derived feature flags.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/AppConfigurationSnapshotPropertySource.java	Refactors snapshot property loading path to process settings locally and then process feature flags.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/AzureAppConfigDataLoader.java	Wires FeatureFlagClient into application setting property source creation.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/http/policy/TracingInfo.java	Adds snapshot reference usage tracking and emits SnapshotRef in the Features correlation context.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/main/java/com/azure/spring/cloud/appconfiguration/config/implementation/AppConfigurationConstants.java	Introduces SNAPSHOT_REFERENCE_TAG constant for tracing output.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/test/java/com/azure/spring/cloud/appconfiguration/config/implementation/http/policy/TracingInfoTest.java	Adds/updates tracing tests to validate SnapshotRef feature tagging.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/test/java/com/azure/spring/cloud/appconfiguration/config/implementation/AppConfigurationApplicationSettingPropertySourceTest.java	Adds tests covering snapshot reference resolution and feature flag handling through snapshots.
sdk/spring/spring-cloud-azure-appconfiguration-config/src/test/java/com/azure/spring/cloud/appconfiguration/config/implementation/AppConfigurationPropertySourceKeyVaultTest.java	Updates test setup for the new property source constructor signature.
sdk/spring/spring-cloud-azure-appconfiguration-config/CHANGELOG.md	Documents the new snapshot reference support.