springdoc-openapi-webflux-ui v1.6.7 + spring actuator + spring cloud crashes at startup

[3mtee]

Describe the bug
If your java/kotlin application uses a combination of springdoc-openapi-webflux-ui v1.6.7 + spring actuator + spring cloud stream - it crashes on startup with the message:

***************************
APPLICATION FAILED TO START
***************************

Description:

Parameter 0 of method webConversionServiceProvider in org.springdoc.core.SpringDocConfiguration$WebConversionServiceConfiguration required a single bean, but 2 were found:
	- webFluxConversionService: defined by method 'webFluxConversionService' in class path resource [org/springframework/boot/autoconfigure/web/reactive/WebFluxAutoConfiguration$EnableWebFluxConfiguration.class]
	- integrationConversionService: defined in null

To Reproduce
Steps to reproduce the behavior:

1. Create a new spring boot application at the spring initializr. Add the following dependencies:
   • "Spring Boot Actuator"
   • "Cloud Stream"
   • "Spring Reactive Web"
2. Programming language doesn't matter (I reproduced the bug with Java and Kotlin).
3. Download and unpack the archive.
4. Add the swagger into build.gradle:

implementation("org.springdoc:springdoc-openapi-webflux-ui:1.6.7")

5. Run the app

My build.gradle:

plugins {
    id 'org.springframework.boot' version '2.6.6'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '17'

repositories {
    mavenCentral()
}

ext {
    set('springCloudVersion', "2021.0.1")
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-actuator'
    implementation 'org.springframework.boot:spring-boot-starter-webflux'
    implementation 'org.springframework.cloud:spring-cloud-stream'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'io.projectreactor:reactor-test'

    implementation("org.springdoc:springdoc-openapi-webflux-ui:1.6.7")
}

dependencyManagement {
    imports {
        mavenBom "org.springframework.cloud:spring-cloud-dependencies:${springCloudVersion}"
    }
}

Expected behavior
Web app shouldn't crash

Screenshots
none

Additional context
Versions:

• Spring-boot 2.6.6
• springdoc-openapi-webflux-ui v1.6.7

Any of the following actions fix the problem:

1. change the springdoc-openapi-webflux-ui to v1.6.6
2. remove the spring-boot-starter-actuator dependency
3. remove the spring-cloud-stream dependency

[mshima]

This is probably the same problem #1607.
And is preventing us to migrate to v1.6.7 jhipster/jhipster-bom#744

We have many webflux samples. Only 1 is failing.
Seems a specific scenario.

Edit:
I can confirm that the failing samples uses cloud-stream.

[bnasslahsen]

Thank you @3mtee for the reproducible steps!

@mshima i confirm it's specific to the case when spring-cloud-stream is included.
Should be fixed with the next release.

[mshima]

Thanks @bnasslahsen

[jongidal]

I had the same situation.

[bnasslahsen]

@jongidal,

Use v1.6.8