This may be helpful:
- Log4j2 will first look for log4j2-test.xml in the classpath
- if that file is not found, it will look for log4j2.xml in the classpath
So one option is to copy the library's configuration (log4j2.xml) to log4j2-test.xml and add your own configuration to log4j2-test.xml.
Furthermore, Log4j2 supports XInclude in XML configuration, so you could use that feature to avoid duplicating the library's configuration in your log4j2-test.xml.