Multiple SL4J bindings error

[tbruyelle]

While I completely remove other logback dependencies in my project (confirmed by checking the dependency report, only the logback plugin requires the logback artifacts), I get this error :

$ grails clean
| Configuring classpath
| Error SLF4J: Class path contains multiple SLF4J bindings.
| Error SLF4J: Found binding in [jar:file:/Users/tbruyelle/.grails/ivy-cache/org.grails.plugins/logback/jars/logback-0.1.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
| Error SLF4J: Found binding in [jar:file:/Users/tbruyelle/.grails/ivy-cache/ch.qos.logback/logback-classic/jars/logback-classic-1.0.9.jar!/org/slf4j/impl/StaticLoggerBinder.class]
| Error SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
| Error WARN in Logger[org.springframework.core.io.support.PathMatchingResourcePatternResolver] - No appenders present in context [default] for logger [org.springframework.core.io.support.PathMatchingResourcePatternResolver].
| Application cleaned.

Despite the error, the log is working as expected with the appenders I configured, but I just wonder why this error is raised.

[tbruyelle]

I looked at the sources and I found a class named StaticLoggerBinder, which seems to fail the check of slf4j multiple bindings.