project/plugins.sbt (4 lines of code) (raw):
addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.3.1")
addSbtPlugin("com.michaelpollmeier" % "sbt-assembly-log4j2" % "1.1.3")
addSbtPlugin("com.gu" % "sbt-riffraff-artifact" % "1.1.18")
addDependencyTreePlugin