diff --git a/akka-http-core/src/main/scala/akka/http/util/package.scala b/akka-http-core/src/main/scala/akka/http/util/package.scala
index b26931c1d7..0ac503fdf7 100644
--- a/akka-http-core/src/main/scala/akka/http/util/package.scala
+++ b/akka-http-core/src/main/scala/akka/http/util/package.scala
@@ -8,8 +8,7 @@ import language.implicitConversions
 import language.higherKinds
 import java.nio.charset.Charset
 import com.typesafe.config.Config
-import akka.stream.FlattenStrategy
-import akka.stream.scaladsl.{ Flow, Source }
+import akka.stream.scaladsl.{ FlattenStrategy, Flow, Source }
 import akka.stream.stage._
 import scala.concurrent.duration.Duration
 import scala.concurrent.{ Await, Future }
diff --git a/akka-http-core/src/test/scala/akka/http/engine/parsing/RequestParserSpec.scala b/akka-http-core/src/test/scala/akka/http/engine/parsing/RequestParserSpec.scala
index dcb29884f9..006eda03e7 100644
--- a/akka-http-core/src/test/scala/akka/http/engine/parsing/RequestParserSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/engine/parsing/RequestParserSpec.scala
@@ -11,7 +11,7 @@ import org.scalatest.{ BeforeAndAfterAll, FreeSpec, Matchers }
 import org.scalatest.matchers.Matcher
 import akka.stream.scaladsl._
 import akka.stream.scaladsl.OperationAttributes._
-import akka.stream.FlattenStrategy
+import akka.stream.scaladsl.FlattenStrategy
 import akka.stream.ActorFlowMaterializer
 import akka.util.ByteString
 import akka.actor.ActorSystem
diff --git a/akka-http-core/src/test/scala/akka/http/engine/parsing/ResponseParserSpec.scala b/akka-http-core/src/test/scala/akka/http/engine/parsing/ResponseParserSpec.scala
index bc661930e1..ddd8adaeb6 100644
--- a/akka-http-core/src/test/scala/akka/http/engine/parsing/ResponseParserSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/engine/parsing/ResponseParserSpec.scala
@@ -11,7 +11,7 @@ import org.scalatest.{ BeforeAndAfterAll, FreeSpec, Matchers }
 import org.scalatest.matchers.Matcher
 import akka.stream.scaladsl._
 import akka.stream.scaladsl.OperationAttributes._
-import akka.stream.FlattenStrategy
+import akka.stream.scaladsl.FlattenStrategy
 import akka.stream.ActorFlowMaterializer
 import akka.util.ByteString
 import akka.actor.ActorSystem
diff --git a/akka-http/src/main/scala/akka/http/marshalling/MultipartMarshallers.scala b/akka-http/src/main/scala/akka/http/marshalling/MultipartMarshallers.scala
index 64c92165d2..79060a288f 100644
--- a/akka-http/src/main/scala/akka/http/marshalling/MultipartMarshallers.scala
+++ b/akka-http/src/main/scala/akka/http/marshalling/MultipartMarshallers.scala
@@ -8,7 +8,7 @@ import akka.event.{ NoLogging, LoggingAdapter }
 
 import scala.concurrent.forkjoin.ThreadLocalRandom
 import akka.parboiled2.util.Base64
-import akka.stream.FlattenStrategy
+import akka.stream.scaladsl.FlattenStrategy
 import akka.stream.scaladsl._
 import akka.http.engine.rendering.BodyPartRenderer
 import akka.http.util.FastFuture
diff --git a/akka-stream-tck/src/test/scala/akka/stream/tck/FlattenTest.scala b/akka-stream-tck/src/test/scala/akka/stream/tck/FlattenTest.scala
index 72a7600065..15510414fd 100644
--- a/akka-stream-tck/src/test/scala/akka/stream/tck/FlattenTest.scala
+++ b/akka-stream-tck/src/test/scala/akka/stream/tck/FlattenTest.scala
@@ -3,10 +3,10 @@
  */
 package akka.stream.tck
 
+import akka.stream.scaladsl.FlattenStrategy
 import akka.stream.scaladsl.Sink
 import akka.stream.scaladsl.Source
 import org.reactivestreams.Publisher
-import akka.stream.FlattenStrategy
 
 class FlattenTest extends AkkaPublisherVerification[Int] {
 
diff --git a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConcatAllSpec.scala b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConcatAllSpec.scala
index a5132a0953..e3ec71c402 100644
--- a/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConcatAllSpec.scala
+++ b/akka-stream-tests/src/test/scala/akka/stream/scaladsl/FlowConcatAllSpec.scala
@@ -5,7 +5,6 @@ package akka.stream.scaladsl
 
 import scala.concurrent.duration._
 import scala.util.control.NoStackTrace
-import akka.stream.FlattenStrategy
 import akka.stream.ActorFlowMaterializer
 import akka.stream.ActorFlowMaterializerSettings
 import akka.stream.testkit.{ StreamTestKit, AkkaSpec }
diff --git a/akka-stream/src/main/boilerplate/akka/stream/javadsl/BidiFlowCreate.scala.template b/akka-stream/src/main/boilerplate/akka/stream/javadsl/BidiFlowCreate.scala.template
index eb8641d4a8..a443368b43 100644
--- a/akka-stream/src/main/boilerplate/akka/stream/javadsl/BidiFlowCreate.scala.template
+++ b/akka-stream/src/main/boilerplate/akka/stream/javadsl/BidiFlowCreate.scala.template
@@ -5,7 +5,6 @@ package akka.stream.javadsl
 
 import akka.stream.scaladsl
 import akka.stream.{ Inlet, Outlet, Shape, Graph, BidiShape }
-import akka.stream.scaladsl.JavaConverters._
 import akka.japi.Pair
 
 trait BidiFlowCreate {
diff --git a/akka-stream/src/main/boilerplate/akka/stream/javadsl/FlowCreate.scala.template b/akka-stream/src/main/boilerplate/akka/stream/javadsl/FlowCreate.scala.template
index 64ca7ddd32..01e4f4445a 100644
--- a/akka-stream/src/main/boilerplate/akka/stream/javadsl/FlowCreate.scala.template
+++ b/akka-stream/src/main/boilerplate/akka/stream/javadsl/FlowCreate.scala.template
@@ -5,7 +5,6 @@ package akka.stream.javadsl
 
 import akka.stream.scaladsl
 import akka.stream.{ Inlet, Outlet, Shape, Graph }
-import akka.stream.scaladsl.JavaConverters._
 import akka.japi.Pair
 
 trait FlowCreate {
diff --git a/akka-stream/src/main/boilerplate/akka/stream/javadsl/GraphCreate.scala.template b/akka-stream/src/main/boilerplate/akka/stream/javadsl/GraphCreate.scala.template
index 37cf4a82b1..c3ed28ff9d 100644
--- a/akka-stream/src/main/boilerplate/akka/stream/javadsl/GraphCreate.scala.template
+++ b/akka-stream/src/main/boilerplate/akka/stream/javadsl/GraphCreate.scala.template
@@ -5,7 +5,6 @@ package akka.stream.javadsl
 
 import akka.stream.scaladsl
 import akka.stream.{ Inlet, Shape, Graph }
-import akka.stream.scaladsl.JavaConverters._
 
 trait GraphCreate {
 
diff --git a/akka-stream/src/main/boilerplate/akka/stream/javadsl/SinkCreate.scala.template b/akka-stream/src/main/boilerplate/akka/stream/javadsl/SinkCreate.scala.template
index fa33ff0a54..b78be90d2d 100644
--- a/akka-stream/src/main/boilerplate/akka/stream/javadsl/SinkCreate.scala.template
+++ b/akka-stream/src/main/boilerplate/akka/stream/javadsl/SinkCreate.scala.template
@@ -5,7 +5,6 @@ package akka.stream.javadsl
 
 import akka.stream.scaladsl
 import akka.stream.{ Inlet, Shape, Graph }
-import akka.stream.scaladsl.JavaConverters._
 
 trait SinkCreate {
 
diff --git a/akka-stream/src/main/boilerplate/akka/stream/javadsl/SourceCreate.scala.template b/akka-stream/src/main/boilerplate/akka/stream/javadsl/SourceCreate.scala.template
index e12a470106..cd0b097358 100644
--- a/akka-stream/src/main/boilerplate/akka/stream/javadsl/SourceCreate.scala.template
+++ b/akka-stream/src/main/boilerplate/akka/stream/javadsl/SourceCreate.scala.template
@@ -5,7 +5,6 @@ package akka.stream.javadsl
 
 import akka.stream.scaladsl
 import akka.stream.{ Outlet, Shape, Graph }
-import akka.stream.scaladsl.JavaConverters._
 
 trait SourceCreate {
 
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/FlattenStrategy.scala b/akka-stream/src/main/scala/akka/stream/javadsl/FlattenStrategy.scala
index 18a140659a..bcda86b3c6 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/FlattenStrategy.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/FlattenStrategy.scala
@@ -3,7 +3,12 @@
  */
 package akka.stream.javadsl
 
-import akka.stream.javadsl
+import akka.stream.scaladsl
+
+/**
+ * Strategy that defines how a stream of streams should be flattened into a stream of simple elements.
+ */
+abstract class FlattenStrategy[-S, T] extends scaladsl.FlattenStrategy[S, T]
 
 object FlattenStrategy {
 
@@ -12,8 +17,11 @@ object FlattenStrategy {
    * emitting its elements directly to the output until it completes and then taking the next stream. This has the
    * consequence that if one of the input stream is infinite, no other streams after that will be consumed from.
    */
-  def concat[T]: akka.stream.FlattenStrategy[javadsl.Source[T, Unit], T] =
-    akka.stream.FlattenStrategy.Concat[T]().asInstanceOf[akka.stream.FlattenStrategy[javadsl.Source[T, _], T]]
-  // TODO so in theory this should be safe, but let's rethink the design later
+  def concat[T]: FlattenStrategy[Source[T, Unit], T] = Concat[T]()
+
+  /**
+   * INTERNAL API
+   */
+  private[akka] final case class Concat[T]() extends FlattenStrategy[Source[T, _], T]
 
 }
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
index 67bec8b44c..e54c1d8e7a 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
@@ -14,8 +14,6 @@ import akka.stream.impl.StreamLayout
 
 object Flow {
 
-  import akka.stream.scaladsl.JavaConverters._
-
   val factory: FlowCreate = new FlowCreate {}
 
   /** Adapt [[scaladsl.Flow]] for use within Java DSL */
@@ -44,12 +42,11 @@ object Flow {
 /** Create a `Flow` which can process elements of type `T`. */
 class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends Graph[FlowShape[In, Out], Mat] {
   import scala.collection.JavaConverters._
-  import akka.stream.scaladsl.JavaConverters._
 
   override def shape: FlowShape[In, Out] = delegate.shape
   private[stream] def module: StreamLayout.Module = delegate.module
 
-  /** Converts this Flow to it's Scala DSL counterpart */
+  /** Converts this Flow to its Scala DSL counterpart */
   def asScala: scaladsl.Flow[In, Out, Mat] = delegate
 
   /**
@@ -401,7 +398,7 @@ class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends Graph
    * Transforms a stream of streams into a contiguous stream of elements using the provided flattening strategy.
    * This operation can be used on a stream of element type [[Source]].
    */
-  def flatten[U](strategy: akka.stream.FlattenStrategy[Out, U]): javadsl.Flow[In, U, Mat] =
+  def flatten[U](strategy: FlattenStrategy[Out, U]): javadsl.Flow[In, U, Mat] =
     new Flow(delegate.flatten(strategy))
 
   /**
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Graph.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Graph.scala
index 85e3e5eb73..3a765947aa 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Graph.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Graph.scala
@@ -279,7 +279,7 @@ object FlowGraph {
    */
   def builder[M](): Builder[M] = new Builder()(new scaladsl.FlowGraph.Builder[M])
 
-  final class Builder[Mat]()(private implicit val delegate: scaladsl.FlowGraph.Builder[Mat]) { self ⇒
+  final class Builder[+Mat]()(private implicit val delegate: scaladsl.FlowGraph.Builder[Mat]) { self ⇒
     import akka.stream.scaladsl.FlowGraph.Implicits._
 
     def flow[A, B, M](from: Outlet[A], via: Flow[A, B, M], to: Inlet[B]): Unit = delegate.addEdge(from, via.asScala, to)
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Sink.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Sink.scala
index 6010845443..96dc483c39 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Sink.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Sink.scala
@@ -17,8 +17,6 @@ import scala.util.Try
 /** Java API */
 object Sink {
 
-  import akka.stream.scaladsl.JavaConverters._
-
   val factory: SinkCreate = new SinkCreate {}
 
   /** Adapt [[scaladsl.Sink]] for use within Java DSL */
@@ -116,7 +114,7 @@ class Sink[-In, +Mat](delegate: scaladsl.Sink[In, Mat]) extends Graph[SinkShape[
   override def shape: SinkShape[In] = delegate.shape
   private[stream] def module: StreamLayout.Module = delegate.module
 
-  /** Converts this Sink to it's Scala DSL counterpart */
+  /** Converts this Sink to its Scala DSL counterpart */
   def asScala: scaladsl.Sink[In, Mat] = delegate
 
   /**
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
index 5875727e63..eba226a3bd 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
@@ -23,8 +23,6 @@ import scala.annotation.varargs
 /** Java API */
 object Source {
 
-  import scaladsl.JavaConverters._
-
   val factory: SourceCreate = new SourceCreate {}
 
   /** Adapt [[scaladsl.Source]] for use within JavaDSL */
@@ -181,14 +179,12 @@ object Source {
  * Can be used as a `Publisher`
  */
 class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Graph[SourceShape[Out], Mat] {
-  import akka.stream.scaladsl.JavaConverters._
-
   import scala.collection.JavaConverters._
 
   override def shape: SourceShape[Out] = delegate.shape
   private[stream] def module: StreamLayout.Module = delegate.module
 
-  /** Converts this Java DSL element to it's Scala DSL counterpart. */
+  /** Converts this Java DSL element to its Scala DSL counterpart. */
   def asScala: scaladsl.Source[Out, Mat] = delegate
 
   /**
@@ -472,7 +468,7 @@ class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Graph[Sour
    * Transforms a stream of streams into a contiguous stream of elements using the provided flattening strategy.
    * This operation can be used on a stream of element type [[Source]].
    */
-  def flatten[U](strategy: akka.stream.FlattenStrategy[Out, U]): javadsl.Source[U, Mat] =
+  def flatten[U](strategy: FlattenStrategy[Out, U]): javadsl.Source[U, Mat] =
     new Source(delegate.flatten(strategy))
 
   /**
diff --git a/akka-stream/src/main/scala/akka/stream/FlattenStrategy.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/FlattenStrategy.scala
similarity index 77%
rename from akka-stream/src/main/scala/akka/stream/FlattenStrategy.scala
rename to akka-stream/src/main/scala/akka/stream/scaladsl/FlattenStrategy.scala
index 64b88105d3..290db28f6b 100644
--- a/akka-stream/src/main/scala/akka/stream/FlattenStrategy.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/FlattenStrategy.scala
@@ -1,12 +1,14 @@
 /**
  * Copyright (C) 2009-2014 Typesafe Inc. <http://www.typesafe.com>
  */
-package akka.stream
+package akka.stream.scaladsl
+
+import akka.stream.javadsl
 
 /**
  * Strategy that defines how a stream of streams should be flattened into a stream of simple elements.
  */
-abstract class FlattenStrategy[-T, U]
+abstract class FlattenStrategy[-S, T]
 
 object FlattenStrategy {
 
@@ -15,7 +17,7 @@ object FlattenStrategy {
    * emitting its elements directly to the output until it completes and then taking the next stream. This has the
    * consequence that if one of the input stream is infinite, no other streams after that will be consumed from.
    */
-  def concat[T]: FlattenStrategy[scaladsl.Source[T, _], T] = Concat[T]()
+  def concat[T]: FlattenStrategy[Source[T, _], T] = Concat[T]()
 
-  private[akka] final case class Concat[T]() extends FlattenStrategy[scaladsl.Source[T, _], T]
+  private[akka] final case class Concat[T]() extends FlattenStrategy[Source[T, _], T]
 }
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
index c11b587595..96dcd09382 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
@@ -286,6 +286,9 @@ final class Flow[-In, +Out, +Mat](private[stream] override val module: Module)
     this.section[O, O2, Mat2, Mat2](attributes, Keep.right)(section)
   }
 
+  /** Converts this Scala DSL element to it's Java DSL counterpart. */
+  def asJava: javadsl.Flow[In, Out, Mat] = new javadsl.Flow(this)
+
 }
 
 object Flow extends FlowApply {
@@ -627,8 +630,8 @@ trait FlowOps[+Out, +Mat] {
    * Transforms a stream of streams into a contiguous stream of elements using the provided flattening strategy.
    * This operation can be used on a stream of element type [[akka.stream.scaladsl.Source]].
    */
-  def flatten[U](strategy: akka.stream.FlattenStrategy[Out, U]): Repr[U, Mat] = strategy match {
-    case _: FlattenStrategy.Concat[Out] ⇒ andThen(ConcatAll())
+  def flatten[U](strategy: FlattenStrategy[Out, U]): Repr[U, Mat] = strategy match {
+    case _: FlattenStrategy.Concat[Out] | _: javadsl.FlattenStrategy.Concat[Out] ⇒ andThen(ConcatAll())
     case _ ⇒
       throw new IllegalArgumentException(s"Unsupported flattening strategy [${strategy.getClass.getName}]")
   }
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
index d17c3f572c..574330107f 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
@@ -297,6 +297,9 @@ object FlowGraph extends GraphApply {
 
     private[stream] def module: Module = moduleInProgress
 
+    /** Converts this Scala DSL element to it's Java DSL counterpart. */
+    def asJava: javadsl.FlowGraph.Builder[M] = new javadsl.FlowGraph.Builder()(this)
+
   }
 
   object Implicits {
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/JavaConverters.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/JavaConverters.scala
deleted file mode 100644
index 093aba8d5e..0000000000
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/JavaConverters.scala
+++ /dev/null
@@ -1,45 +0,0 @@
-/**
- * Copyright (C) 2014 Typesafe Inc. <http://www.typesafe.com>
- */
-package akka.stream.scaladsl
-
-import akka.stream.javadsl
-import akka.stream.scaladsl
-
-/**
- * Implicit converters allowing to convert between Java and Scala DSL elements.
- */
-private[akka] object JavaConverters {
-
-  implicit final class AddAsJavaSource[Out, Mat](val source: scaladsl.Source[Out, Mat]) extends AnyVal {
-    def asJava: javadsl.Source[Out, Mat] = new javadsl.Source(source)
-  }
-  implicit final class AddAsJavaFlow[In, Out, Mat](val flow: scaladsl.Flow[In, Out, Mat]) extends AnyVal {
-    def asJava: javadsl.Flow[In, Out, Mat] = new javadsl.Flow(flow)
-  }
-  implicit final class AddAsJavaBidiFlow[I1, O1, I2, O2, Mat](val flow: scaladsl.BidiFlow[I1, O1, I2, O2, Mat]) extends AnyVal {
-    def asJava: javadsl.BidiFlow[I1, O1, I2, O2, Mat] = new javadsl.BidiFlow(flow)
-  }
-  implicit final class AddAsJavaSink[In, Mat](val sink: scaladsl.Sink[In, Mat]) extends AnyVal {
-    def asJava: javadsl.Sink[In, Mat] = new javadsl.Sink(sink)
-  }
-  implicit final class AsAsJavaFlowGraphBuilder[Out, Mat](val builder: scaladsl.FlowGraph.Builder[Mat]) extends AnyVal {
-    def asJava: javadsl.FlowGraph.Builder[Mat] = new javadsl.FlowGraph.Builder()(builder)
-  }
-
-  implicit final class AddAsScalaSource[Out, Mat](val source: javadsl.Source[Out, Mat]) extends AnyVal {
-    def asScala: scaladsl.Source[Out, Mat] = source.asScala
-  }
-  implicit final class AddAsScalaFlow[In, Out, Mat](val flow: javadsl.Flow[In, Out, Mat]) extends AnyVal {
-    def asScala: scaladsl.Flow[In, Out, Mat] = flow.asScala
-  }
-  implicit final class AddAsScalaBidiFlow[I1, O1, I2, O2, Mat](val flow: javadsl.BidiFlow[I1, O1, I2, O2, Mat]) extends AnyVal {
-    def asScala: scaladsl.BidiFlow[I1, O1, I2, O2, Mat] = flow.asScala
-  }
-  implicit final class AddAsScalaSink[In, Mat](val sink: javadsl.Sink[In, Mat]) extends AnyVal {
-    def asScala: scaladsl.Sink[In, Mat] = sink.asScala
-  }
-  implicit final class AsAsScalaFlowGraphBuilder[Out, Mat](val builder: javadsl.FlowGraph.Builder[Mat]) extends AnyVal {
-    def asScala: FlowGraph.Builder[Mat] = builder.asScala
-  }
-}
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Sink.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Sink.scala
index f5436c7024..f8faaf94be 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Sink.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Sink.scala
@@ -3,6 +3,7 @@
  */
 package akka.stream.scaladsl
 
+import akka.stream.javadsl
 import akka.actor.{ ActorRef, Props }
 import akka.stream.impl._
 import akka.stream.{ SinkShape, Inlet, Outlet, Graph }
@@ -40,6 +41,9 @@ final class Sink[-In, +Mat](private[stream] override val module: Module)
     new Sink(module.withAttributes(attr).wrap())
 
   def named(name: String): Sink[In, Mat] = withAttributes(OperationAttributes.name(name))
+
+  /** Converts this Scala DSL element to it's Java DSL counterpart. */
+  def asJava: javadsl.Sink[In, Mat] = new javadsl.Sink(this)
 }
 
 object Sink extends SinkApply {
diff --git a/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala b/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
index 14ed935920..776c918086 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Source.scala
@@ -3,6 +3,7 @@
  */
 package akka.stream.scaladsl
 
+import akka.stream.javadsl
 import akka.stream.impl.Stages.{ MaterializingStageFactory, StageModule }
 import akka.stream.{ SourceShape, Inlet, Outlet }
 import akka.stream.impl.StreamLayout.{ EmptyModule, Module }
@@ -152,6 +153,9 @@ final class Source[+Out, +Mat](private[stream] override val module: Module)
   override def withAttributes(attr: OperationAttributes): Repr[Out, Mat] =
     new Source(module.withAttributes(attr).wrap())
 
+  /** Converts this Scala DSL element to it's Java DSL counterpart. */
+  def asJava: javadsl.Source[Out, Mat] = new javadsl.Source(this)
+
 }
 
 object Source extends SourceApply {