Problem is that idea shows warning if you dont have a blank line following the header in a file. My environment is:
scalaVersion: "2.12.4"
sbt.version: "1.1.5"
addSbtPlugin("org.scalastyle" %% "scalastyle-sbt-plugin" % "1.0.0")
You can disable this headerchecker from scalastyle_config.xml file.
<check level="warning" class="org.scalastyle.file.HeaderMatchesChecker" enabled="false">
This will solve the problem and won’t run checker