source: https://github.com/apache/logging-log4j2/blob/rel/2.14.0/NOTICE.txt

Apache Log4j
Copyright 1999-2017 Apache Software Foundation

This product includes software developed at
The Apache Software Foundation (http://www.apache.org/).

ResolverUtil.java
Copyright 2005-2006 Tim Fennell

Dumbster SMTP test server
Copyright 2004 Jason Paul Kitchen

TypeUtil.java
Copyright 2002-2012 Ramnivas Laddad, Juergen Hoeller, Chris Beams

picocli (http://picocli.info)
Copyright 2017 Remko Popma