An internal "DSL" in Scala for setting up authorization rules programmatically in ActiveMQ

Example.scala

def authorizationPlugin: BrokerPlugin = {
  val dsl = new AuthorizationDSL; import dsl._

  val system = Set(User("system"))

  entry(Queue(">"), r = system, w = system, a = system)
  entry(Topic(">"), r = system, w = system, a = system)

  Seq("test").foreach { basename =>
    val client = Set(User(basename + "-client"))
    val server = Set(User(basename + "-server"))
    val both   = client ++ server

    entry(Topic("ActiveMQ.Advisory.>"),        r = both,   w = both,   a = both)
    entry(Queue(basename + ".to-server"),      r = server, w = both,   a = both)
    entry(Queue(basename + ".to-one-client"),  r = client, w = server, a = both)
    entry(Topic(basename + ".to-all-clients"), r = client, w = server, a = both)
  }

  makePlugin()
}

Implementation.scala

import org.apache.activemq.broker._
import org.apache.activemq.command._
import org.apache.activemq.filter._
import org.apache.activemq.jaas._
import org.apache.activemq.security._

import scala.collection.JavaConverters._

class AuthorizationDSL {
  def Queue(name: String) = new ActiveMQQueue (name)
  def Topic(name: String) = new ActiveMQTopic (name)
  def User (name: String) = new UserPrincipal (name)
  def Group(name: String) = new GroupPrincipal(name)

  val authEntries = new java.util.ArrayList[DestinationMapEntry[_]]()

  def entry(destination: ActiveMQDestination, r: Set[UserPrincipal], w: Set[UserPrincipal], a: Set[UserPrincipal]) {
    def objectify[T[_]](m: T[_]): T[Object] = m.asInstanceOf[T[Object]]

    val authEntry = new AuthorizationEntry()
    authEntry.setDestination(destination)
    authEntry.setReadACLs (objectify(r.asJava))
    authEntry.setWriteACLs(objectify(w.asJava))
    authEntry.setAdminACLs(objectify(a.asJava))
    authEntries.add(authEntry)
  }

  def makePlugin() = new AuthorizationPlugin(new DefaultAuthorizationMap(authEntries))
}