App Config - Head Requests

[mrm9084]

Description

Adds head request support to the Java SDK.

See Python: Azure/azure-sdk-for-python#45858
See JS: Azure/azure-sdk-for-js#36959

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 HEAD-request support to the Azure App Configuration Java SDK to enable efficient change detection via page-level ETags, without downloading response bodies.

Changes:

• Added checkConfigurationSettings APIs to both sync (ConfigurationClient) and async (ConfigurationAsyncClient) clients, backed by the service’s HEAD /kv endpoint.
• Added unit tests covering HEAD paging behavior (empty items, page ETag presence) and ETag change detection.
• Added a new sample demonstrating polling-style change detection with cached page ETags, and updated the changelog.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
sdk/appconfiguration/azure-data-appconfiguration/src/main/java/com/azure/data/appconfiguration/ConfigurationClient.java	Adds sync checkConfigurationSettings API and JavaDoc samples.
sdk/appconfiguration/azure-data-appconfiguration/src/main/java/com/azure/data/appconfiguration/ConfigurationAsyncClient.java	Adds async checkConfigurationSettings API and JavaDoc samples.
sdk/appconfiguration/azure-data-appconfiguration/src/main/java/com/azure/data/appconfiguration/implementation/Utility.java	Adds helpers to translate HEAD responses into PagedResponse and handle 304 for HEAD, plus continuation parsing.
sdk/appconfiguration/azure-data-appconfiguration/src/test/java/com/azure/data/appconfiguration/ConfigurationClientTest.java	Adds sync tests for HEAD paging and ETag change detection.
sdk/appconfiguration/azure-data-appconfiguration/src/test/java/com/azure/data/appconfiguration/ConfigurationAsyncClientTest.java	Adds async tests for HEAD paging and ETag change detection.
sdk/appconfiguration/azure-data-appconfiguration/src/samples/java/com/azure/data/appconfiguration/CheckConfigurationSettingsForChanges.java	New sample demonstrating HEAD-based change detection using page ETags + If-None-Match.
sdk/appconfiguration/azure-data-appconfiguration/src/main/java/com/azure/data/appconfiguration/package-info.java	Updates package-level instantiation snippets.
sdk/appconfiguration/azure-data-appconfiguration/src/main/java/com/azure/data/appconfiguration/ConfigurationClientBuilder.java	Updates builder JavaDoc instantiation/pipeline snippets.
sdk/appconfiguration/azure-data-appconfiguration/CHANGELOG.md	Documents the new checkConfigurationSettings feature.