in sbt-idea-compiler-indices/src/main/scala/org/jetbrains/sbt/indices/IntellijIndexer.scala [127:134]
def notifyFinish(socket: Socket, result: CompilationResult): Unit = {
val in = new DataInputStream(socket.getInputStream())
val out = new DataOutputStream(socket.getOutputStream())
out.writeBoolean(result.successful)
result.infoFile.foreach(f => out.writeUTF(f.getPath))
val ack = in.readUTF()
if (ack != ideaACK) throw new RuntimeException("Malformed response from IDEA.")
}