Fix passthrough additionalProperties fallback for models with typed properties

[lohanidamodar]

What changed

Two related fixes for the model passthrough/additionalProperties handling. Sister PR on the Appwrite side that emits the spec: appwrite/appwrite#12403.

1. Fix the regression in fromMap fallback (commit 1)

Commit 171408b (PR #1543) added a definition.properties | length > 0 branch around the ?? fallback in the dart/kotlin/android Model templates. Models that have BOTH typed properties AND outer additionalProperties: true (Document, Row, Presence, etc.) ended up emitting an empty-map fallback (?? {} / ?: emptyMap()), which silently drops user payloads when the response is inline (e.g. Row's user columns live at the top level next to $id, not nested under a data key).

This restores the unconditional whole-map fallback so the same code path that worked before #1543 keeps working. Swift template is unaffected — it uses Codable and never had the branch.

2. Drop the x-additional-properties-key vendor extension (commit 2)

The extension let an Appwrite response model declare a custom name (e.g. metadata) for the passthrough field in the generated SDK, on top of marking the outer schema as additionalProperties: true. This conflated two distinct OpenAPI 3 concepts:

• Outer-level additionalProperties: true — extras are inline siblings of typed properties. Standard.
• Nested free-form object — express as a regular property of type object with additionalProperties: true on that property. Standard.

The vendor extension was being used to model the second case via the first one, which required generator-side special handling and made sdk-generator non-portable for anyone consuming a vanilla OpenAPI 3 spec.

This PR removes:

• the x-additional-properties-key reading from src/Spec/Swagger2.php,
• the definition.additionalPropertiesKey | default('data') lookup from every template that used it (dart, kotlin, android, swift, php, dotnet, ruby, rust, python — model and test templates).

All templates now emit the literal 'data' field name for inline-passthrough models — same default as before. The sister Appwrite PR (#12403) migrates the one consumer (Presence) to a normal typed metadata property and removes the emission side of the extension.

Why now

After #12403 lands, no Appwrite spec will emit x-additional-properties-key anymore. The reading was already dead in CI: mock-server/ (the spec source for sdk-generator's integration tests) has no models that use the extension.

Verification

• composer lint-twig: 539 files, 0 errors.
• Regenerated dart/kotlin/android example SDKs spot-checked: Row, Document, Presence-equivalent models all emit ?? map (whole-map fallback) in fromMap again.

[greptile-apps]

Greptile Summary

This PR delivers two coordinated fixes: it restores the unconditional whole-map fallback in fromMap/from(map:) for mixed models (those with both typed properties and additionalProperties: true) across Dart, Kotlin, Android, and Swift, reversing a regression from #1543; and it removes the x-additional-properties-key vendor extension from the parser and all 10 language templates, hardcoding the field name to 'data' in preparation for the companion Appwrite spec PR (#12403) that eliminates the only consumer of that extension.

• Regression fix: The {% if definition.properties | length > 0 %} branch introduced in Presence api #1543 has been removed from Dart, Kotlin, Android, and Swift templates. All four now use a single unconditional path (?? map / ?: map.jsonCast(…) / ?? map) so models like Row and Document, whose user columns live at the top level of the API response rather than nested under a "data" key, deserialize correctly again.
• Vendor extension removal: additionalPropertiesKey is dropped from Swagger2::getDefinitions() and getRequestModels(), and every template that referenced definition.additionalPropertiesKey | default('data') now uses the literal 'data'. PHP, Python, Ruby, Rust, and .NET are purely mechanical substitutions; their deserialization logic was never affected by the regression.

Confidence Score: 5/5

Safe to merge; all changed paths have been cross-checked and the whole-map fallback is correctly restored for every affected language.

The regression fix is straightforward and consistent across all four affected templates. The vendor-extension removal is mechanical — every template that read additionalPropertiesKey now emits the literal 'data', which was the default value in every case. The companion Appwrite spec PR removes the only emitter of x-additional-properties-key, so no in-flight spec will silently produce the wrong field name. The previously flagged Swift from(map:) issue is also resolved in this PR.

No files require special attention.

Important Files Changed

Filename	Overview
src/Spec/Swagger2.php	Removes additionalPropertiesKey from both getDefinitions() and getRequestModels() — straightforward, no fallback left behind.
templates/dart/lib/src/models/model.dart.twig	Removes the `properties
templates/kotlin/src/main/kotlin/io/appwrite/models/Model.kt.twig	Identical regression fix to Dart — removes `properties
templates/android/library/src/main/java/io/package/models/Model.kt.twig	Same regression fix as Kotlin — collapses the two-branch fromMap to a single unconditional whole-map fallback.
templates/swift/Sources/Models/Model.swift.twig	Removes the `properties
templates/php/src/Models/Model.php.twig	Only replaces the additionalPropertiesKey variable with the literal 'data'; the PHP deserialization path (extractAdditionalPropertiesFromFields) was never affected by the regression.
templates/dotnet/Package/Models/Model.cs.twig	Replaces additionalPropertiesKey with literal 'data'; the TryGetValue(…) : map whole-map fallback was already present and unaffected by the regression.
templates/python/package/models/model.py.twig	Replaces additionalPropertiesKey with 'data' in 10 spots across the property declaration, getter/setter, and to_dict; no logic changes.
templates/ruby/lib/container/models/model.rb.twig	Replaces additionalPropertiesKey with 'data'; the `map["data"]
templates/rust/src/models/model.rs.twig	Replaces additionalPropertiesKey with 'data' in the struct field, accessor, and get helper; no logic changes.

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