Spring @RequestScope does not work as intended when used with @Bean for Kotlin class

Hi,

I created this issue with the springboot team and they referred me here : https://github.com/spring-projects/spring-boot/issues/40858

I am using springboot 2.7.14 and running Java 17.

I have created this class:

class RequestContextHolder {
    private var headers: Map<String, String?>? = null

    fun setHeaders(headers: Map<String, String?>) {
        this.headers = headers
    }

    fun getHeaders(): Map<String, String?>? {
        return this.headers
    }
}

Declared it as a request scoped bean here:

    @Bean
    @RequestScope
    fun requestContextHolder(): RequestContextHolder {
        return RequestContextHolder()
    }

Used the bean as a dependency in my web filter as follows

@Component
class AppRequestContextFilter(
    private val requestContextHolder: RequestContextHolder
) : OncePerRequestFilter() {
---
}

But as opposed to my expectation, the instance of RequestContextHolder being returned seems to retain the values from the previous requests.

This issue goes away if I instead do the following and make the RequestContextHolder class a Spring component.

@Component
@RequestScope
class RequestContextHolder {
    private var headers: Map<String, String?>? = null

    fun setHeaders(headers: Map<String, String?>) {
        this.headers = headers
    }

    fun getHeaders(): Map<String, String?>? {
        return this.headers
    }
}

Is this inconsistency between @Component and @Bean expected? If so, I do not see it documented anywhere. Please clarify.

Comment From: snicoll

Did you try any of the suggestions before creating this issue?

Is this inconsistency between @Component and @Bean expected?

No. It should work whether you put it on @Bean or the type itself. If you want support, please share a small sample we can run ourselves with instructions on how to reproduce. You can attach a zip to this issue or push the code to a separate GitHub repository.

Comment From: sbrannen

I'm guessing the difference might be that the presence of @Component is causing the class to be open due to the kotlin-spring plugin (thanks to @sdeleuze for the link).

@mgunasekha-chwy, what happens if you make that non-annotated class open via open class RequestContextHolder?

Comment From: mgunasekha-chwy

@sbrannen I tried declaring the RequestContextHolder as open to no success when using @Bean. The issue still reproduces in this case

Comment From: mgunasekha-chwy

@snicoll There were a couple of suggestions in the other thread. I tried the suggestion about adding proxymode and that did not resolve the issue. Also I am using @RequestScope which is an alias for adding a proxymode anyway, so not sure if that changes anything. : https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/web/context/annotation/RequestScope.html

About the other suggestion to use an ObjectProvider, that sounded like a workaround and I am happy to use @Component in that case.

I just wanted to flag this in case it is a bug that need to be fixed within the framework.

Comment From: sbrannen

Thanks for trying out open and providing feedback, @mgunasekha-chwy.

As @snicoll mentioned, if you'd like us to investigate this further...

please share a small sample we can run ourselves with instructions on how to reproduce. You can attach a zip to this issue or push the code to a separate GitHub repository.

Comment From: spring-projects-issues

If you would like us to look at this issue, please provide the requested information. If the information is not provided within the next 7 days this issue will be closed.

Comment From: sbrannen

Is this inconsistency between @Component and @Bean expected? If so, I do not see it documented anywhere.

It turns out this is to be expected, and it is documented in the Spring Projects in Kotlin section of the reference manual.

Some use cases involving proxies and automatic generation of final methods by the Kotlin compiler require extra care. For example, a Kotlin class with properties will generate related final getters and setters. In order to be able to proxy related methods, a type level @Component annotation should be preferred to method level @Bean in order to have those methods opened by the kotlin-spring plugin. A typical use case is @Scope and its popular @RequestScope specialization.

@mgunasekha-chwy, what happens if you make the class and its methods open as follows?

open class RequestContextHolder {
    private var headers: Map<String, String?>? = null

    open fun setHeaders(headers: Map<String, String?>) {
        this.headers = headers
    }

    open fun getHeaders(): Map<String, String?>? {
        return this.headers
    }
}

Comment From: spring-projects-issues

Closing due to lack of requested feedback. If you would like us to look at this issue, please provide the requested information and we will re-open the issue.