Script to download all library sources into a target directory

DownloadSources.scala

import sbt._, Keys._

object DownloadSources extends AutoPlugin {
  override def trigger = allRequirements
  override def requires = sbt.plugins.JvmPlugin
  override def projectSettings = 
    List(Compile, Test).flatMap { config =>
      inConfig(config)(
        TaskKey[Seq[File]]("downloadSources") := Def.task[Seq[File]] {
          val out = baseDirectory.in(ThisBuild).value / "target" / "sources"
          val sourceJars = for {
            configurationReport <- updateClassifiers.value.configurations
            moduleReport <- configurationReport.modules
            (artifact, file) <- moduleReport.artifacts
            if artifact.classifier.exists(_ == "sources")
            _ = IO.unzip(file, out)
          } yield file
          sourceJars.distinct
        }.value
      )
    }
}

At the root of your sbt build run the following commands

wget -O project/DownloadSources.scala https://gist.githubusercontent.com/olafurpg/02cef3995f9ef702fa055b4cee90ac98/raw/d04cfe95650b234a830a3f53634ca58dab50fec7/DownloadSources.scala
sbt "all downloadSources"
cd target/sources
grep "???" # Enjoy!