chore: remove leftover Scala 2.12 idioms

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/internal/BehaviorTestKitImpl.scala

@@ -16,7 +16,6 @@ package org.apache.pekko.actor.testkit.typed.internal
 import java.util
 
 import scala.annotation.tailrec
-import scala.collection.immutable
 import scala.jdk.CollectionConverters._
 import scala.reflect.ClassTag
 import scala.util.control.Exception.Catcher
@@ -104,7 +103,7 @@ private[pekko] final class BehaviorTestKitImpl[T](
 
   override def selfInbox(): TestInboxImpl[T] = context.selfInbox
 
-  override def retrieveAllEffects(): immutable.Seq[Effect] = {
+  override def retrieveAllEffects(): Seq[Effect] = {
     @tailrec def rec(acc: List[Effect]): List[Effect] = context.effectQueue.poll() match {
       case null => acc.reverse
       case x    => rec(x :: acc)
@@ -202,7 +201,7 @@ private[pekko] final class BehaviorTestKitImpl[T](
 
   override def getAllLogEntries(): util.List[CapturedLogEvent] = logEntries().asJava
 
-  override def logEntries(): immutable.Seq[CapturedLogEvent] = context.logEntries
+  override def logEntries(): Seq[CapturedLogEvent] = context.logEntries
 
   override def clearLog(): Unit = context.clearLog()
 

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/internal/TestInboxImpl.scala

@@ -16,7 +16,6 @@ package org.apache.pekko.actor.testkit.typed.internal
 import java.util.concurrent.ConcurrentLinkedQueue
 
 import scala.annotation.tailrec
-import scala.collection.immutable
 
 import org.apache.pekko
 import pekko.actor.{ ActorPath, Address, RootActorPath }
@@ -51,7 +50,7 @@ private[pekko] final class TestInboxImpl[T](path: ActorPath)
     this
   }
 
-  override protected def internalReceiveAll(): immutable.Seq[T] = {
+  override protected def internalReceiveAll(): Seq[T] = {
     @tailrec def rec(acc: List[T]): List[T] = q.poll() match {
       case null => acc.reverse
       case x    => rec(x :: acc)

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/internal/TestProbeImpl.scala

@@ -20,7 +20,6 @@ import java.util.concurrent.LinkedBlockingDeque
 import java.util.function.Supplier
 
 import scala.annotation.tailrec
-import scala.collection.immutable
 import scala.concurrent.duration._
 import scala.jdk.CollectionConverters._
 import scala.jdk.DurationConverters._
@@ -251,10 +250,10 @@ private[pekko] final class TestProbeImpl[M](name: String, system: ActorSystem[?]
     }
   }
 
-  override def receiveMessages(n: Int): immutable.Seq[M] =
+  override def receiveMessages(n: Int): Seq[M] =
     receiveMessages_internal(n, remainingOrDefault)
 
-  override def receiveMessages(n: Int, max: FiniteDuration): immutable.Seq[M] =
+  override def receiveMessages(n: Int, max: FiniteDuration): Seq[M] =
     receiveMessages_internal(n, max.dilated)
 
   override def receiveSeveralMessages(n: Int): JList[M] =
@@ -263,7 +262,7 @@ private[pekko] final class TestProbeImpl[M](name: String, system: ActorSystem[?]
   override def receiveSeveralMessages(n: Int, max: JDuration): JList[M] =
     receiveMessages_internal(n, max.toScala.dilated).asJava
 
-  private def receiveMessages_internal(n: Int, max: FiniteDuration): immutable.Seq[M] = {
+  private def receiveMessages_internal(n: Int, max: FiniteDuration): Seq[M] = {
     val stop = max + now
     for (x <- 1 to n) yield {
       val timeout = stop - now
@@ -275,17 +274,17 @@ private[pekko] final class TestProbeImpl[M](name: String, system: ActorSystem[?]
     }
   }
 
-  override def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): immutable.Seq[M] =
+  override def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): Seq[M] =
     fishForMessage_internal(max.dilated, hint, fisher)
 
   override def fishForMessagePF(max: FiniteDuration, hint: String)(
-      fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M] =
+      fisher: PartialFunction[M, FishingOutcome]): Seq[M] =
     fishForMessage(max, hint)(fisher)
 
-  override def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): immutable.Seq[M] =
+  override def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): Seq[M] =
     fishForMessage(max, "")(fisher)
 
-  override def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M] =
+  override def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): Seq[M] =
     fishForMessage(max)(fisher)
 
   override def fishForMessage(max: JDuration, fisher: java.util.function.Function[M, FishingOutcome]): JList[M] =

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/javadsl/TestInbox.scala

@@ -15,7 +15,6 @@ package org.apache.pekko.actor.testkit.typed.javadsl
 
 import java.util.concurrent.ThreadLocalRandom
 
-import scala.collection.immutable
 import scala.jdk.CollectionConverters._
 
 import org.apache.pekko
@@ -71,7 +70,7 @@ abstract class TestInbox[T] {
    */
   def getAllReceived(): java.util.List[T] = internalReceiveAll().asJava
 
-  protected def internalReceiveAll(): immutable.Seq[T]
+  protected def internalReceiveAll(): Seq[T]
 
   def hasMessages: Boolean
 

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/scaladsl/BehaviorTestKit.scala

@@ -15,7 +15,6 @@ package org.apache.pekko.actor.testkit.typed.scaladsl
 
 import java.util.concurrent.ThreadLocalRandom
 
-import scala.collection.immutable
 import scala.reflect.ClassTag
 
 import org.apache.pekko
@@ -115,7 +114,7 @@ trait BehaviorTestKit[T] {
    * Requests all the effects. The effects are consumed, subsequent calls will only
    * see new effects.
    */
-  def retrieveAllEffects(): immutable.Seq[Effect]
+  def retrieveAllEffects(): Seq[Effect]
 
   /**
    * Returns if there have been any effects.
@@ -174,7 +173,7 @@ trait BehaviorTestKit[T] {
   /**
    * Returns all the [[CapturedLogEvent]] issued by this behavior(s)
    */
-  def logEntries(): immutable.Seq[CapturedLogEvent]
+  def logEntries(): Seq[CapturedLogEvent]
 
   /**
    * Clear the log entries

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/scaladsl/TestInbox.scala

@@ -15,8 +15,6 @@ package org.apache.pekko.actor.testkit.typed.scaladsl
 
 import java.util.concurrent.ThreadLocalRandom
 
-import scala.collection.immutable
-
 import org.apache.pekko
 import pekko.Done
 import pekko.actor.{ Address, RootActorPath }
@@ -68,9 +66,9 @@ trait TestInbox[T] {
   /**
    * Collect all messages in the inbox and clear it out
    */
-  def receiveAll(): immutable.Seq[T] = internalReceiveAll()
+  def receiveAll(): Seq[T] = internalReceiveAll()
 
-  protected def internalReceiveAll(): immutable.Seq[T]
+  protected def internalReceiveAll(): Seq[T]
 
   def hasMessages: Boolean
 

actor-testkit-typed/src/main/scala/org/apache/pekko/actor/testkit/typed/scaladsl/TestProbe.scala

@@ -13,7 +13,6 @@
 
 package org.apache.pekko.actor.testkit.typed.scaladsl
 
-import scala.collection.immutable
 import scala.concurrent.duration._
 import scala.reflect.ClassTag
 
@@ -179,14 +178,14 @@ object TestProbe {
   /**
    * Same as `receiveMessages(n, remaining)` but using the default timeout as deadline.
    */
-  def receiveMessages(n: Int): immutable.Seq[M]
+  def receiveMessages(n: Int): Seq[M]
 
   /**
    * Receive `n` messages in a row before the given deadline.
    *
    * Note that the timeout is scaled using the configuration entry "pekko.actor.testkit.typed.timefactor".
    */
-  def receiveMessages(n: Int, max: FiniteDuration): immutable.Seq[M]
+  def receiveMessages(n: Int, max: FiniteDuration): Seq[M]
 
   /**
    * Allows for flexible matching of multiple messages within a timeout, the fisher function is fed each incoming
@@ -206,22 +205,22 @@ object TestProbe {
    *            The timeout is scaled using the configuration entry "pekko.actor.testkit.typed.timefactor".
    * @return The messages accepted in the order they arrived
    */
-  def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): immutable.Seq[M]
+  def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): Seq[M]
 
   /**
    * Same as `fishForMessage` but accepting a partial function and failing for non-matches
    */
-  def fishForMessagePF(max: FiniteDuration, hint: String)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M]
+  def fishForMessagePF(max: FiniteDuration, hint: String)(fisher: PartialFunction[M, FishingOutcome]): Seq[M]
 
   /**
    * Same as the other `fishForMessage` but with no hint
    */
-  def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): immutable.Seq[M]
+  def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): Seq[M]
 
   /**
    * Same as `fishForMessage` but with no hint, accepting a partial function and failing for non-matches
    */
-  def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M]
+  def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): Seq[M]
 
   /**
    * Expect the given actor to be stopped or stop within the given timeout or

actor-tests/src/test/scala/org/apache/pekko/actor/DynamicAccessSpec.scala

@@ -13,7 +13,6 @@
 
 package org.apache.pekko.actor
 
-import scala.collection.immutable
 import scala.concurrent.Await
 import scala.concurrent.duration._
 import scala.util.{ Failure, Success, Try }
@@ -97,7 +96,7 @@ class DynamicAccessSpec extends AnyWordSpec with Matchers with BeforeAndAfterAll
     "preserve the target exception from a failing constructor" in {
       val result = dynamicAccess.createInstanceFor[TestClassWithThrowingConstructor](
         classOf[TestClassWithThrowingConstructor],
-        immutable.Seq(classOf[String] -> "ignored"))
+        Seq(classOf[String] -> "ignored"))
       val exception = result.failed.get
       exception shouldBe a[IllegalArgumentException]
       exception.getMessage should ===("user-bug")
@@ -118,7 +117,7 @@ class DynamicAccessSpec extends AnyWordSpec with Matchers with BeforeAndAfterAll
         case s: Success[TestSuperclass]        => s
         case Failure(_: NoSuchMethodException) =>
           dynamicAccess
-            .createInstanceFor[TestSuperclass](fqcn, immutable.Seq((classOf[String], "string ctor argument")))
+            .createInstanceFor[TestSuperclass](fqcn, Seq((classOf[String], "string ctor argument")))
         case f: Failure[?] => f
       }
 

actor-tests/src/test/scala/org/apache/pekko/actor/RelativeActorPathSpec.scala

@@ -16,14 +16,12 @@ package org.apache.pekko.actor
 import java.net.URLEncoder
 import java.nio.charset.StandardCharsets
 
-import scala.collection.immutable
-
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpec
 
 class RelativeActorPathSpec extends AnyWordSpec with Matchers {
 
-  def elements(path: String): immutable.Seq[String] = RelativeActorPath.unapply(path).getOrElse(Nil)
+  def elements(path: String): Seq[String] = RelativeActorPath.unapply(path).getOrElse(Nil)
 
   "RelativeActorPath" must {
     "match single name" in {

actor-tests/src/test/scala/org/apache/pekko/io/SimpleDnsCacheSpec.scala

@@ -16,7 +16,6 @@ package org.apache.pekko.io
 import java.net.InetAddress
 import java.util.concurrent.atomic.AtomicLong
 
-import scala.collection.immutable
 import scala.concurrent.duration._
 
 import org.apache.pekko
@@ -38,7 +37,7 @@ class SimpleDnsCacheSpec extends AnyWordSpec with Matchers {
       val ttl = Ttl.fromPositive(5000.millis)
       val cacheEntry = DnsProtocol.Resolved(
         "test.local",
-        immutable.Seq(ARecord("test.local", ttl, InetAddress.getByName("127.0.0.1"))))
+        Seq(ARecord("test.local", ttl, InetAddress.getByName("127.0.0.1"))))
       cache.put(("test.local", Ip()), cacheEntry, ttl)
 
       cache.cached(DnsProtocol.Resolve("test.local")) should ===(Some(cacheEntry))
@@ -57,7 +56,7 @@ class SimpleDnsCacheSpec extends AnyWordSpec with Matchers {
       val cacheEntry =
         DnsProtocol.Resolved(
           "test.local",
-          immutable.Seq(ARecord("test.local", ttl, InetAddress.getByName("127.0.0.1"))))
+          Seq(ARecord("test.local", ttl, InetAddress.getByName("127.0.0.1"))))
       cache.put(("test.local", Ip()), cacheEntry, ttl)
 
       cache.cached(DnsProtocol.Resolve("test.local")) should ===(Some(cacheEntry))

actor-tests/src/test/scala/org/apache/pekko/io/TcpConnectionSpec.scala

@@ -24,7 +24,6 @@ import java.nio.file.Files
 import java.util.Random
 
 import scala.annotation.tailrec
-import scala.collection.immutable
 import scala.concurrent.duration._
 import scala.util.Try
 import scala.util.control.NonFatal
@@ -962,7 +961,7 @@ class TcpConnectionSpec extends PekkoSpec("""
 
     def createConnectionActor(
         serverAddress: InetSocketAddress = serverAddress,
-        options: immutable.Seq[SocketOption] = Nil,
+        options: Seq[SocketOption] = Nil,
         timeout: Option[FiniteDuration] = None,
         pullMode: Boolean = false): TestActorRef[TcpOutgoingConnection] = {
       val ref = createConnectionActorWithoutRegistration(serverAddress, options, timeout, pullMode)
@@ -981,7 +980,7 @@ class TcpConnectionSpec extends PekkoSpec("""
 
     def createConnectionActorWithoutRegistration(
         serverAddress: InetSocketAddress = serverAddress,
-        options: immutable.Seq[SocketOption] = Nil,
+        options: Seq[SocketOption] = Nil,
         timeout: Option[FiniteDuration] = None,
         pullMode: Boolean = false): TestActorRef[TcpOutgoingConnection] =
       TestActorRef(

actor-tests/src/test/scala/org/apache/pekko/io/dns/internal/AsyncDnsManagerSpec.scala

@@ -13,8 +13,6 @@
 
 package org.apache.pekko.io.dns.internal
 
-import scala.collection.immutable.Seq
-
 import org.apache.pekko
 import pekko.io.Dns
 import pekko.io.dns.AAAARecord

actor-tests/src/test/scala/org/apache/pekko/io/dns/internal/TcpDnsClientSpec.scala

@@ -15,8 +15,6 @@ package org.apache.pekko.io.dns.internal
 
 import java.net.InetSocketAddress
 
-import scala.collection.immutable.Seq
-
 import org.apache.pekko
 import pekko.actor.{ ActorKilledException, Kill, Props }
 import pekko.io.Tcp

actor-tests/src/test/scala/org/apache/pekko/routing/ConfiguredLocalRoutingSpec.scala

@@ -127,7 +127,7 @@ class ConfiguredLocalRoutingSpec
     case _ => throw new IllegalArgumentException(s"Unexpected actorref $ref")
   }
 
-  def collectRouteePaths(probe: TestProbe, router: ActorRef, n: Int): immutable.Seq[ActorPath] = {
+  def collectRouteePaths(probe: TestProbe, router: ActorRef, n: Int): Seq[ActorPath] = {
     for (i <- 1 to n) yield {
       val msg = i.toString
       router.tell(msg, probe.ref)