-Xlint:-nullary-unit
'.<plugin>
<groupId>net.alchim31.maven</groupId>
<artifactId>scala-maven-plugin</artifactId>
...
<configuration>
...
<args>
<arg>-Xfatal-warnings</arg>
<arg>-deprecation</arg>
<arg>-Xlint:-nullary-unit</arg>
...