src/main/resources/log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration>
  <Appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%5p (%F:%L) -> %m%n"/>
    </Console>
  </Appenders>
  <Loggers>
    <Root level="error">
      <AppenderRef ref="Console"/>
    </Root>
    <!--
    <Logger name="org.glassfish.grizzly.http.server.NetworkListener"
            level="trace">
      <AppenderRef ref="Console"/>
    </Logger>
    <Logger name="de.ids_mannheim.korap.KrillIndex"
            level="trace">
      <AppenderRef ref="Console"/>
    </Logger>
    -->
  </Loggers>
</Configuration>