[BUG][KOTLIN][SPRING] Wildcard path generates invalid code

[chriptus13]

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• Have you tested with the latest master to confirm the issue still exists?
• 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)

Description

When using the cli generator with the spec provided using kotlin-spring generator it produces code that does not compile due to inline comments introduced with version 7.18.0.

openapi-generator version

I tested with multiple versions and looks like the issues starts happening with version 7.18.0

Generated code with version 7.17.0

/**
 * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech) (7.17.0).
 * https://openapi-generator.tech
 * Do not edit the class manually.
*/
package org.openapitools.api

import io.swagger.v3.oas.annotations.*
import io.swagger.v3.oas.annotations.enums.*
import io.swagger.v3.oas.annotations.media.*
import io.swagger.v3.oas.annotations.responses.*
import io.swagger.v3.oas.annotations.security.*
import org.springframework.http.HttpStatus
import org.springframework.http.MediaType
import org.springframework.http.ResponseEntity

import org.springframework.web.bind.annotation.*
import org.springframework.validation.annotation.Validated
import org.springframework.web.context.request.NativeWebRequest
import org.springframework.beans.factory.annotation.Autowired

import jakarta.validation.constraints.DecimalMax
import jakarta.validation.constraints.DecimalMin
import jakarta.validation.constraints.Email
import jakarta.validation.constraints.Max
import jakarta.validation.constraints.Min
import jakarta.validation.constraints.NotNull
import jakarta.validation.constraints.Pattern
import jakarta.validation.constraints.Size
import jakarta.validation.Valid

import kotlinx.coroutines.flow.Flow
import kotlin.collections.List
import kotlin.collections.Map

@RestController
@Validated
interface ProxyApi {

    @Operation(
        tags = ["Proxy",],
        summary = "Proxies all GET requests",
        operationId = "proxyAllGet",
        description = """""",
        responses = [
        ]
    )
    @RequestMapping(
            method = [RequestMethod.GET],
            value = ["/foo/**"]
    )
    suspend fun proxyAllGet(): ResponseEntity<Unit> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }
}

Generated code with version 7.18.0

/**
 * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech) (7.18.0).
 * https://openapi-generator.tech
 * Do not edit the class manually.
*/
package org.openapitools.api

import io.swagger.v3.oas.annotations.*
import io.swagger.v3.oas.annotations.enums.*
import io.swagger.v3.oas.annotations.media.*
import io.swagger.v3.oas.annotations.responses.*
import io.swagger.v3.oas.annotations.security.*
import org.springframework.http.HttpStatus
import org.springframework.http.MediaType
import org.springframework.http.ResponseEntity

import org.springframework.web.bind.annotation.*
import org.springframework.validation.annotation.Validated
import org.springframework.web.context.request.NativeWebRequest
import org.springframework.beans.factory.annotation.Autowired

import jakarta.validation.constraints.DecimalMax
import jakarta.validation.constraints.DecimalMin
import jakarta.validation.constraints.Email
import jakarta.validation.constraints.Max
import jakarta.validation.constraints.Min
import jakarta.validation.constraints.NotNull
import jakarta.validation.constraints.Pattern
import jakarta.validation.constraints.Size
import jakarta.validation.Valid

import kotlinx.coroutines.flow.Flow
import kotlin.collections.List
import kotlin.collections.Map

@RestController
@Validated
interface ProxyApi {

    @Operation(
        tags = ["Proxy",],
        summary = "Proxies all GET requests",
        operationId = "proxyAllGet",
        description = """""",
        responses = [
        ]
    )
    @RequestMapping(
        method = [RequestMethod.GET],
        value = [PATH_PROXY_ALL_GET /* "/foo/**" */]
    )
    suspend fun proxyAllGet(@Parameter(hidden = true) exchange: org.springframework.web.server.ServerWebExchange): ResponseEntity<Unit> {
        return ResponseEntity(HttpStatus.NOT_IMPLEMENTED)
    }

    companion object {
        //for your own safety never directly reuse these path definitions in tests
        const val PATH_PROXY_ALL_GET: String = "/foo/**"
    }
}

OpenAPI declaration file content or url

openapi: 3.1.1
info:
  title: OAS
  version: 1.0.0
servers:
  - url: http://localhost:8080
paths:
  '/foo/**':
    get:
      tags:
        - Proxy
      summary: Proxies all GET requests
      operationId: proxyAllGet
      responses: {}

Generation Details

openapi-generator-cli generate -i spec.yaml -g kotlin-spring --additional-properties=includeHttpRequestContext=true,interfaceOnly=true,reactive=true,useSpringBoot3=true,useTags=true

Steps to reproduce

Use the CLI to generate the code using the provided spec.

Related issues/PRs

Suggest a fix

[Picazsoo]

Hello, I am afraid that your path is not valid open api. Standard OpenAPI does not support double wildcards. So I would vote to close this issue.

[chriptus13]

Hello, I am afraid that your path is not valid open api. Standard OpenAPI does not support double wildcards. So I would vote to close this issue.

Hm, in that case wouldn't it make sense for openapi-generator-cli validate to fail?

[Picazsoo]

I guess it would. I have no idea how well that validator works - I have no experience with that part of the code.

Sorry to be so defensive in this case. The reason is that I introduced the change that is now causing the issues for you. I was eager to go ahead and fix it, but now that I see that the API is simply not valid in the first place, I feel a bit relieved.

[chriptus13]

I guess it would. I have no idea how well that validator works - I have no experience with that part of the code.

Sorry to be so defensive in this case. The reason is that I introduced the change that is now causing the issues for you. I was eager to go ahead and fix it, but now that I see that the API is simply not valid in the first place, I feel a bit relieved.

No worries, I was reading through the specification https://swagger.io/specification and I can't find anything mentioning wildcards. However when loading this spec over in the Swagger editor it does work and doesn't trigger any warning.

[chriptus13]

I believe it would come from https://datatracker.ietf.org/doc/html/rfc3986#section-3.3 mentioned on the "Path Templating" section:

[chriptus13]

Either way I believe having that comment there (on the RequestMapping's value field from the annotation) does not add any value. What you think?

[Picazsoo]

I checked the validating library - https://github.com/swagger-api/swagger-parser. And it indeed does not correctly pick up the thing as invalid. See https://github.com/swagger-api/swagger-parser/blob/master/modules/swagger-parser-v3/src/main/java/io/swagger/v3/parser/util/OpenAPIDeserializer.java#L901 - this is the only validation regarding allowed characters as far as I can tell.

Regarding the comment - I thought the benefit is for quick code navigation - searching through the source code. One less indirection step. Since by moving the path string to its own variable makes it a bit harder to navigate in the code.
Maybe a solution would be to make it into a // comment instead of an inline comment? And place it above?

In the meantime you can fix the issue by pulling the affected mustache files and adjusting them yourself and supplying them via templateDir ?

But the question is whether the project should be guided by incorrect spec. Maybe it should be tolerant to such non-standard things. I have my opinion on that but I might be wrong.