GeezerVison

Step 5 of the plan in #461, for v11 on beta. It replaces the prototype in #486, which kept the 10.x API. Here the OpenAPI spec is the reference, and every place the generated API moves is recorded in MIGRATION.md. This branch is based on beta with main merged in, so the API-gate and ModelObjects work it builds on is already present; the diff is the codegen change only.

codegen/requests.yaml maps each of the 106 data request classes to its spec operationId in one line, with a handful of entries recording a deliberate departure from the spec: the eight typed search classes, top artists and tracks, the reorder/replace split of one operation, the recommendations method's arguments, and one model the spec doesn't have. codegen/generate.py renders every request class from spec/openapi.yaml: the verb, path, query, path and body parameters with their Java types and argument checks, the Javadoc and deprecation, and how the response is read, including paging and cursor paging. It also writes the SpotifyApi method that creates each request, between // <generated-…> markers. Two classes stay hand-written: GetUsersTopArtistsAndTracksRequest (generic over its item type) and AddCustomPlaylistCoverImageRequest (JPEG body). A new CI step regenerates the classes and fails when they differ from what's committed.

The generated API follows the spec. A SpotifyApi method takes the operation's required parameters, typed like their setters, and optional parameters go on the builder; the old varargs, String[] and JsonArray overloads are gone. Each setter has the wire name, so additionalTypes becomes additional_types, includeExternal becomes include_external, snapshotId becomes snapshot_id, and public becomes public_. A body array is a List<String> and a body object a Map<String, Object> instead of Gson JsonArray/JsonObject, which AbstractRequest serializes; an array of one-field objects such as [{"uri": …}] takes the field values and wraps them, so removePlaylistItems still takes plain URIs. If a parameter exists in both the query and the body, only the query one is offered, because Spotify ignores the body copy when both are sent. POST and PUT always send a JSON body, as before.

All the caller-facing changes are listed in MIGRATION.md, taken from japicmp's report against 10.1.0 (66 removed and 49 added signatures, 2 changed return types). GetSeveralAudiobooksRequest returns Audiobook[] and GetCategoryPlaylistsRequest returns FeaturedPlaylists, following the response schema. country, timestamp and album_type are removed because the spec no longer has them. Two fixes fall out of following the spec: GetRecentlyPlayedTracksRequest.after/before now send Unix milliseconds instead of a formatted date, and deprecation now matches the spec everywhere, so followPlaylist and saveTracksForCurrentUser are deprecated.

Verified locally: 420 tests pass, codegen/generate.py --check reports no drift, ci/check-docs.py checks all 115 examples, Javadoc passes doclint, and the examples module compiles.