DATAREST-1036-ruthes00. Added support for If-None-Match: * with PUT requests

[ruthst00]

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Overview

Added support for If-None-Match: * with PUT requests, implementing RFC 7232 §3.2 semantics (create-only guard). The following files were changed:

• ETag.java: — Added WILDCARD_ETAG constant (representing *) and a new verifyNoneMatch(PersistentEntity, Object) method that throws ETagDoesntMatchException when the ETag is a wildcard and the target resource already exists.

• RepositoryEntityController.java: — Added a @RequestHeader HttpHeaders requestHeaders parameter to putItemResource. When If-None-Match: * is present, the handler looks up the existing resource by ID and calls ETag.WILDCARD_ETAG.verifyNoneMatch(...) — if the resource exists, a 412 Precondition Failed is returned (via the existing ETagDoesntMatchException handler); if it doesn't exist, the PUT proceeds normally as a creation.

• ETagUnitTests.java: — Added 4 unit tests covering: wildcard throws when resource exists, wildcard passes when resource is null, NO_ETAG never rejects, and ETag.from("*") equals WILDCARD_ETAG.

• RepositoryEntityControllerIntegrationTests.java: — Updated all existing putItemResource calls to pass the new HttpHeaders parameter, and added 2 new integration tests: one verifying a PUT with If-None-Match: * succeeds (201) when the resource doesn't exist, and one verifying it fails with ETagDoesntMatchException when the resource already exists.

• etags-and-other-conditionals.adoc: — Added a new If-None-Match: * with PUT subsection explaining the create-only guard semantics with a curl example.