Make log4j display which file it used to configure itself?

Notes to myself:

simply add log4j.debug to the JVM system variables. For example:

java -Dlog4j.debug -cp ... some.class.name
  

Log4j FAQ

Could not create plugin of type 'MatrixTestingPlugin'

After forked and cloned Hibernate-orm project from Github, I tried to compile the project using

./gradlew clean build

But I'm kept getting error:

Could not create plugin of type 'MatrixTestingPlugin'

I checked my environment, I have "JAVA_HOME" configured. I even have had previously installed gradle removed.

Eventually, I figured the problem is that the path of "JAVA_HOME" has the empty space, and gradle 1.5 failed to recognize that. So after moved Java into a location with no space in the path, the problem solved.