In Confluence, we have a lot of property pairs in log4j.properties like this:

log4j.logger.com.atlassian.confluence.core=DEBUG, confluencelog
log4j.additivity.com.atlassian.confluence.core=false

This sets the core package logging level to DEBUG, and ensures it only gets printed once in the log. The additivity line isn't necessary if we remove the ",confluencelog" from the end of the logger property – confluencelog is already appended to by the rootLogger so it doesn't need to be added again.

We should change examples like the above to simply this:

log4j.logger.com.atlassian.confluence.core=DEBUG