Question mark (?) symbol printed in java Stack Trace

Question

I am running Fuse ESB SOAP service on a karaf docker container.

JAAS Basic authentication is implemented in this service. For wrong credentials, I am getting expected authentication error in the fuse logs but I am also getting? symbol in the java stack trace logs. Below is the snapshot of logs with? symbol highlighted.

Also I am not getting any such? symbol, when the same code is run in an older version of karaf. (pictures attached)

With? symbol. 4.2.6.fuse-750016-redhat-00001

Without? symbol 2.4.0.redhat-630262

Answer 1

If you're using Fuse 7.5, then what's rendering the stack trace is org.apache.logging.log4j.core.impl.ExtendedStackTraceElement class used by pax-logging 1.11 and pax-logging-log4j2 used by Fuse 7.

Fuse 6.x on the other hand uses pax-logging 1.9.1 and pax-logging-service bundle, which is based on Log4j1 and the rendering of stack trace elements depend on... Karaf's endorsed $FUSE_HOME/lib/endorsed/org.apache.karaf.exception-2.4.0.redhat-630262.jar library.

So simply - the stack traces are formatted using different mechanisms.