Caused by: org.apache.logging.log4j.LoggingException: log4j-slf4j-impl cannot be present with log4j-to-slf4j

[mklueh]

I cannot use hawtio with the latest version in our application. It clashes with Spring Dependencies

These are our dependencies:

//springVersion=2.7.2
//springCloudVersion=2021.0.3

dependencies {
        implementation "org.springframework.boot:spring-boot-starter"

        implementation "org.springframework.boot:spring-boot-starter-web"
        implementation "org.springframework.boot:spring-boot-starter-aop"
        implementation "org.springframework.boot:spring-boot-starter-jdbc"
        implementation "org.springframework.boot:spring-boot-starter-cache"
        implementation "org.springframework.boot:spring-boot-starter-log4j2"
        implementation 'org.springframework.boot:spring-boot-starter-actuator'
        implementation "org.springframework.boot:spring-boot-starter-data-jpa"
        implementation "org.springframework.boot:spring-boot-starter-data-rest"

        implementation 'org.springframework.cloud:spring-cloud-starter'
        implementation "org.springframework.cloud:spring-cloud-starter-bootstrap"
        implementation "org.springframework.cloud:spring-cloud-starter-openfeign"

        implementation 'org.springdoc:springdoc-openapi-ui:1.6.9'
        implementation 'io.hawt:hawtio-springboot:2.15.0'
}

configurations {
    all {
        //noinspection GroovyAssignabilityCheck
        exclude group: 'org.springframework.boot', module: 'spring-boot-starter-logging'
    }
}

And this is the full stacktrace:

SLF4J: Actual binding is of type [org.apache.logging.slf4j.Log4jLoggerFactory]
Exception in thread "main" java.lang.ExceptionInInitializerError
Caused by: org.apache.logging.log4j.LoggingException: log4j-slf4j-impl cannot be present with log4j-to-slf4j
	at org.apache.logging.slf4j.Log4jLoggerFactory.validateContext(Log4jLoggerFactory.java:60)
	at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:44)
	at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:33)
	at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:53)
	at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:33)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:363)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:388)
	at com.mainfirst.pmx.client.Application.<clinit>(Application.java:16)

I'm not that much into the logging chaos of Java and not sure what is mandatory and what can go. Preferably I'd like to keep my application the way it was and use hawtio without the transitive dependency that comes with it.
Would it be possible to make it somehow optional?

[tadayosi]

Relates #2751

[tadayosi]

Fixed #2758