[JAVA-SPRING;KOTLIN-SPRING] bugfix - PagedModel<T> - default to custom DTO; allow override via import mapping and schema mapping

[Picazsoo]

The initial implementation of the functionality had a couple of issues that I only uncovered once I tried to use it in my complex project. schemaMapping overrides of the "content" array Type was not respected by the generator leading to compilation issues. Another issue is that the native org.springframework.data.web.PagedModel is not very easy to deserialize into. So I now default to a custom included DTO. The Dto can be replaced via importMapping with a custom one.

Edit: There is another version of this PR here #23601 which contains identical fixes, but also enables usage of PagedModel as return type in spring declarative interfaces. The change is limited to a couple of modified conditionals and some tests. As always it is opt-in (which seem to be a pretty good idea seeing how I always manage to sneak in at least some bugs - this way the bugs are tightly limited to the new functionality and do not cause regressions)

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---

Summary by cubic

Fixes PagedModel substitution in Spring and Kotlin generators. Defaults to a generated configPackage.PagedModel, and now respects schemaMappings for item types and importMappings.PagedModel (including custom simple names); APIs and samples import the correct type, and docs clarify 'page' metadata detection.

• Bug Fixes

  • Return types use mapped item types and imports (e.g., PagedModel<com.example.external.ExternalUser>).
  • Honors custom importMappings.PagedModel; uses its simple class name (e.g., MyPagedModel<T>) and adds the correct import.
  • Generates configPackage.PagedModel for Java/Kotlin when no custom mapping; samples import org.openapitools.configuration.PagedModel.
  • Docs updated to note 'page' metadata detection and default/override behavior.

• Migration

  • If you used org.springframework.data.web.PagedModel, set importMappings.PagedModel to your class or use the generated configPackage.PagedModel.
  • Verify schemaMappings for item types; API return types will reflect mapped names and imports.

^{Written for commit cc5d628. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 16 files

[cubic-dev-ai]

3 issues found across 5 files (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="docs/generators/java-camel.md">

<violation number="1" location="docs/generators/java-camel.md:107">
P2: Updated docs for `substituteGenericPagedModel` omit the new `importMappings.PagedModel` override behavior, making configuration guidance inaccurate.</violation>
</file>

<file name="docs/generators/kotlin-spring.md">

<violation number="1" location="docs/generators/kotlin-spring.md:61">
P2: `substituteGenericPagedModel` docs imply `configPackage.PagedModel` is always used, but implementation supports `importMappings.PagedModel` and only falls back to generated config package model.</violation>
</file>

<file name="docs/generators/spring.md">

<violation number="1" location="docs/generators/spring.md:100">
P2: `substituteGenericPagedModel` docs are inaccurate: they imply `PagedModel<T>` is always generated in `configPackage`, but behavior can be overridden via `importMappings.PagedModel`.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[cubic-dev-ai]

1 issue found across 1 file (changes from recent commits).

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinSpringServerCodegen.java">

<violation number="1" location="modules/openapi-generator/src/main/java/org/openapitools/codegen/languages/KotlinSpringServerCodegen.java:1224">
P2: Using `putIfAbsent` for the derived paged-model class token can retain a conflicting existing import mapping, causing generated `pagedModelClassName` types to resolve to the wrong class.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}

[wing328]

cc @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03) @stefankoppier (2022/06) @e5l (2024/10) @dennisameling (2026/02)

[Picazsoo]

Just to clarify - actually a typical case here might be using the importMapping to change from PagedModel to org.springframework.data.domain.Page. Then the controller interfaces end up with format such as ResponseEntity<Page<Something>>, which when used together with spring setting @EnableSpringDataWebSupport(pageSerializationMode = VIA_DTO) will automaticall serialize the responses as PagedModel<T> instead of (unsuitable for serialization) Page<T>