[BUG][kotlin-spring] Fix defaultValue for RequestHeader is not generated (#20504)

[cgpoh]

This PR will fix 20504. Copied the current Java spring generator logic for the Kotlin Spring generator.

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@jimschubert (2017/09) ❤️, @dr4ke616 (2018/08) @karismann (2019/03) @Zomzog (2019/04) @andrewemery (2019/10) @4brunu (2019/11) @yutaka0m (2020/03)

[wing328]

https://github.com/OpenAPITools/openapi-generator/actions/runs/14189376808/job/39750844839?pr=21003

please follow step 3 to update the samples

(in windows, you may need to run the command in WSL)

[cgpoh]

@wing328 , thanks! I've updated the samples.

[wing328]

i did a test with the spec provided in the issue but got errors:

$ ./gradlew build

> Task :compileKotlin FAILED
e: file:///C:/Users/wing3/AppData/Local/Temp/kotlin-spring/src/main/kotlin/org/openapitools/api/PetApiController.kt:68:317 Unresolved reference: de

FAILURE: Build failed with an exception.

does it work for your use cases locally with this fix?

[wing328]

and here is the change with this fix (compared with master)

--- a/src/main/kotlin/org/openapitools/api/PetApiController.kt
+++ b/src/main/kotlin/org/openapitools/api/PetApiController.kt
@@ -65,7 +65,7 @@ class PetApiController() {
         method = [RequestMethod.DELETE],
         value = ["/pet/{petId}"]
     )
-    fun deletePet(@Parameter(description = "Pet id to delete", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "", `in` = ParameterIn.HEADER, schema = Schema(allowableValues = ["de", "at"], defaultValue = "de")) @RequestHeader(value = "x-tenant", required = false) xTenant: kotlin.String,@Parameter(description = "", `in` = ParameterIn.HEADER) @RequestHeader(value = "api_key", required = false) apiKey: kotlin.String?): ResponseEntity<Unit> {
+    fun deletePet(@Parameter(description = "Pet id to delete", required = true) @PathVariable("petId") petId: kotlin.Long,@Parameter(description = "", `in` = ParameterIn.HEADER, schema = Schema(allowableValues = ["de", "at"], defaultValue = "de")) @RequestHeader(value = "x-tenant", required = false, defaultValue = de) xTenant: kotlin.String,@Parameter(description = "", `in` = ParameterIn.HEADER) @RequestHeader(value = "api_key", required = false) apiKey: kotlin.String?): ResponseEntity<Unit> {
         return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
     }

[cgpoh]

I just did a ./gradlew build in openapi-generator/samples/server/petstore/kotlin-spring-default and the build is successful. How to replicate the error?

[wing328]

please use https://gist.github.com/wing328/bb5ce7ec9a91527a67b4c0f1a3c95737 to reproduce the issue

[cgpoh]

Thanks @wing328, I have the same error, will debug further.

[wing328]

tested again and the output builds without issue

thanks for the pr

[cgpoh]

Thanks @wing328 for your review :)