feat: sync with ans Discovery Profiles

[jhateley-godaddy]

Related issue

Fixes #87

Summary

Issue #87 asked us to bring the Java SDK to parity with the ANS reference implementation. That implementation shipped Adapter-style DNS Discovery Profiles (agentnameservice/ans#25): the ANS-family DNS discovery styles (SVCB and TXT) and the trust records that go with them.

Most of that sync landed already in commit 9c26e91 (PR #92). That commit regenerated the models from the ANS repo spec. It also added the v1/v2 API routing and the first cut of discoveryProfiles handling. This PR is the final fix on top of that work. It corrects the discoveryProfiles default and the version semantics.

discoveryProfiles is a v2-only field. The v1 lane ignores it on the server.

The first cut defaulted the field to [ANS_DNSAID]. It removed the field from the wire body without notice when the target was v1. That approach hid a client mistake. It also sent a default that the caller did not choose.

Now the behavior is different:

• The default is an empty set. An empty set holds no selection, so the client omits it from the wire body through @JsonInclude(NON_EMPTY).
• An explicit discoveryProfiles selection on the v1 lane is a client misconfiguration. The client rejects it with IllegalArgumentException instead of a silent drop. The message tells the caller to remove the selection or to build the client with ApiVersion.V2.
• On v2, the client sends an explicit selection on the wire. It omits the empty default.

Changes

• AgentRegistrationRequest: the default discoveryProfiles is now an empty LinkedHashSet. The getter has the @JsonInclude(NON_EMPTY) annotation, so the client omits the empty default.
• RegistrationService: added rejectDiscoveryProfilesOnV1. It throws when a caller uses a non-empty selection on v1. Serialization no longer removes the field.
• AnsApiClient: removed the unused serializeToJsonWithoutField JSON-tree helper.

Testing

• Removed AnsApiClientTest, which covered the deleted helper.
• ApiVersionRoutingTest: v1 omits the empty default. v1 rejects an explicit selection before any HTTP call.
• RegistrationClientTest: v2 sends an explicit selection on the wire. v2 omits the empty default.

e2e tests ran against v1 and v2.

AI assistance

Assisted-by: Claude Code (claude-fable-5)

Checklist

• The PR title follows Conventional Commits — release notes are generated from it
• Tests cover the change
• The linked issue above uses a closing keyword
• Every commit is signed off (git commit -s) certifying the DCO

[bchen-godaddy]

LGTM