[BUG] figma OpenAPI specification to kotlin

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
  Was not possible
• Have you tested with the latest master to confirm the issue still exists?
  I've used the latest version.
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)
  I'm willing to sponsor/donate $100 for a fully working kotlin code from the figma openapi specification.

Description

I like to generate kotlin data classes from figma openapi specification

Full example: figmaopenapitokotlin.zip

openapi-generator version

id("org.openapi.generator") version "7.11.0"

OpenAPI file

https://github.com/figma/rest-api-spec/blob/main/openapi/openapi.yaml

Gradle file

group = "org.example"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

dependencies {
    testImplementation(kotlin("test"))
}

tasks.test {
    useJUnitPlatform()
}
kotlin {
    jvmToolchain(11)
}

plugins {
    kotlin("jvm") version "2.0.10"
    application
    id("org.jetbrains.kotlin.plugin.serialization") version "2.1.0"
    id("org.openapi.generator") version "7.11.0"
}

repositories {
    mavenCentral()
}

sourceSets.main {
    java.srcDirs("build/generated-sources/src/main")
}

dependencies {
    implementation("org.jetbrains.kotlinx:kotlinx-serialization-json-jvm:1.8.0")
}

openApiGenerate {
    generatorName.set("kotlin")
    inputSpec.set("$projectDir/src/main/resources/figma/openapi.yaml")
    outputDir.set("$buildDir/generated-sources")
    apiPackage.set("org.example.figmaopenapitokotlin.figmaclient.api") // Package for API classes
    modelPackage.set("org.example.figmaopenapitokotlin.figmaclient.model") // Package for model classes
    invokerPackage.set("org.example.figmaopenapitokotlin.figmaclient.invoker") // Package for supporting classes
    configOptions.set(
        mapOf(
            "dateLibrary" to "java8",
            "serializationLibrary" to "kotlinx_serialization"
        )
    )
    typeMappings.set(
        mapOf(
            // does not work: Too many arguments for 'constructor(): String'.
            "number" to "kotlin.String",
            "decimal" to "kotlin.String"
        )
    )
    globalProperties.set(
        mapOf(
            "models" to "" // Generate only models
        )
    )
    skipValidateSpec.set(true)
}

tasks.register("fixGeneratedCode") {
    group = "build"
    description = "Replaces invalid kotlin.String constructor calls with string literals"

    doLast {
        val generatedSourceDir = file("build/generated-sources") // Adjust the path to match your generated sources directory
        if (generatedSourceDir.exists()) {
            generatedSourceDir.walkTopDown()
                .filter { it.isFile && it.extension == "kt" }
                .forEach { file ->
                    val updatedContent = file.readText()
                        .replace("""kotlin.String\("(.*?)"\)""".toRegex(), "\"$1\"") // Replace kotlin.String("value") with "value"
                    file.writeText(updatedContent)
                }
        } else {
            println("Generated source directory not found: $generatedSourceDir")
        }
    }
}

Generation Details

1. .\gradlew openapigenerate
2. .\gradlew fixGeneratedCode
   To get rid of the string constructor problem
3. .\gradlew assemble

Steps to reproduce

gradlew shows errors

1. Strings are created with a constructor (from number and decimal) which might be easy to solve like my fixGeneratedCode task. But there might be a better solution.
2. There are a lot of errors like

> Task :compileKotlin FAILED
e: file:///C:/Users/bladenth/IdeaProjects/figmaopenapitokotlin/build/generated-sources/src/main/kotlin/org/example/figmaopenapitokotlin/figmaclient/model/ActivityLogEntity.kt:45:1 @Serializable annotation without arguments can be used only on sealed interfaces.Non-sealed interfaces are polymorphically serializable by default.
e: file:///C:/Users/bladenth/IdeaProjects/figmaopenapitokotlin/build/generated-sources/src/main/kotlin/org/example/figmaopenapitokotlin/figmaclient/model/BooleanOperationNode.kt:199:56 Initializer type mismatch: expected 'org.example.figmaopenapitokotlin.figmaclient.model.BooleanOperationNode.LayoutGrow?', actual 'kotlin.String'.

Related issues/PRs

Suggest a fix

Reproduce the generation using the linked Figma openapi.yaml and the shown Gradle openApiGenerate configuration, then inspect the generated ActivityLogEntity.kt and BooleanOperationNode.kt errors. Compare the Kotlin serialization output and number/decimal mappings with the compile failures; done means the generated models compile without the manual fixGeneratedCode task.