SLF4J: Class path contains multiple SLF4J bindings during WSO2 IS startup

Question

One of my WSO2 IS (Identity Server) went poof due to physical host error, and when I want to bring back up the IS service, it just hangs and won't start up right after these warning message:

SLF4J: Class path contains multiple SLF4J bindings.

SLF4J: Found binding in [bundleresource://539.fwk120694604:1/org/slf4j/impl/StaticLoggerBinder.class]

SLF4J: Found binding in [jar:file:/usr/lib64/wso2/wso2is/5.6.0/repository/deployment/server/webapps/api%23identity%23entitlement/WEB-INF/lib/slf4j-simple-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]

Aside of IS process hanging, there is no logs generated as well, so as per the warning messages said, there are conflicting logging classes for WSO2 IS, but I can't find this class whereabout:

bundleresource://539.fwk120694604:1/org/slf4j/impl/StaticLoggerBinder.class

My current WSO2 IS version is 5.6.0 and due to some restriction I can't upgrade the version and I don't think versioning is the issue here.

I had search all over the internet but mostly involve edit pom / maven kinda stuffs but WSO2 IS is supposed to be ready product right? Well, thus until now I still can't find any solution.

Can any kind soul help me with this issue?

Thank you.