SpringBoot Tracing missing in log statement before returning the Mono chain after boot 3.2 webflux upgrade

Hi,

Super simple to reproduce but if I have a simple spring boot webflux application:

@SpringBootApplication
public class SpringBootTracingApplication {

    public static void main(String[] args) {
      Hooks.enableAutomaticContextPropagation();
        SpringApplication.run(SpringBootTracingApplication.class, args);
    }

}

... 

@RestController
@Slf4j
public class MyController {


  @GetMapping
  public Mono<Map<String,String>> home() {
    log.info("enter home()");
    return Mono.just(Map.of("message", "Hello World")).doOnSuccess(response -> log.info("exit home()"));
  };

}

Then in spring boot 3.2 the initial log trace is missing

2023-12-01T12:56:37.949Z  INFO [tid=,sid=] 93573 --- [ctor-http-nio-2] [                                                 ] com.example.demo.MyController            : enter home()
2023-12-01T12:56:37.954Z  INFO [tid=6569d805149e5b057aacd77450367167,sid=7aacd77450367167] 93573 --- [ctor-http-nio-2] [6569d805149e5b057aacd77450367167-7aacd77450367167] com.example.demo.MyController            : exit home()

Where as in spring boot 3.0.x and 3.1.x the trace works as expected:

2023-12-01T12:58:55.777Z  INFO [tid=6569d88f02bf0c298d41dd3354b48abc,sid=8d41dd3354b48abc] 93949 --- [ctor-http-nio-2] com.example.demo.MyController            : enter home()
2023-12-01T12:58:55.783Z  INFO [tid=6569d88f02bf0c298d41dd3354b48abc,sid=8d41dd3354b48abc] 93949 --- [ctor-http-nio-2] com.example.demo.MyController            : exit home()

Thanks

FYI pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>3.2.0</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>spring-boot-tracing</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-tracing</name>
    <description>Demo project for Spring Boot</description> 
    <properties>
        <java.version>17</java.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>   
        <dependency>
            <groupId>io.micrometer</groupId>
            <artifactId>micrometer-tracing</artifactId>
        </dependency>        
        <dependency>
            <groupId>io.micrometer</groupId>
            <artifactId>micrometer-tracing-bridge-brave</artifactId>
        </dependency> 
       <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <scope>provided</scope>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>io.projectreactor</groupId>
            <artifactId>reactor-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

Comment From: mhalbritter

Thanks for the report, I think this is a duplicate of https://github.com/spring-projects/spring-framework/issues/31706.