diff --git a/akka-docs/rst/scala/code/docs/persistence/PersistenceMultiDocSpec.scala b/akka-docs/rst/scala/code/docs/persistence/PersistenceMultiDocSpec.scala
index e66ee0291b..e89573de59 100644
--- a/akka-docs/rst/scala/code/docs/persistence/PersistenceMultiDocSpec.scala
+++ b/akka-docs/rst/scala/code/docs/persistence/PersistenceMultiDocSpec.scala
@@ -21,21 +21,21 @@ object PersistenceMultiDocSpec {
   }
   //#default-plugins
 
-  val OverrideConfig = """
+  val OverrideConfig = s"""
   //#override-config
   # Configuration entry for the custom journal plugin, see `journalPluginId`.
   akka.persistence.chronicle.journal {
     # Standard persistence extension property: provider FQCN.
     class = "akka.persistence.chronicle.ChronicleSyncJournal"
     # Custom setting specific for the journal `ChronicleSyncJournal`.
-    folder = ${user.dir}/store/journal
+    folder = $${user.dir}/store/journal
   }
   # Configuration entry for the custom snapshot store plugin, see `snapshotPluginId`.
   akka.persistence.chronicle.snapshot-store {
     # Standard persistence extension property: provider FQCN.
     class = "akka.persistence.chronicle.ChronicleSnapshotStore"
     # Custom setting specific for the snapshot store `ChronicleSnapshotStore`.
-    folder = ${user.dir}/store/snapshot
+    folder = $${user.dir}/store/snapshot
   }
   //#override-config
   """
diff --git a/akka-http-core/src/test/scala/akka/http/javadsl/HttpExtensionApiSpec.scala b/akka-http-core/src/test/scala/akka/http/javadsl/HttpExtensionApiSpec.scala
index 748371d1a7..dce742fae2 100644
--- a/akka-http-core/src/test/scala/akka/http/javadsl/HttpExtensionApiSpec.scala
+++ b/akka-http-core/src/test/scala/akka/http/javadsl/HttpExtensionApiSpec.scala
@@ -13,7 +13,7 @@ import akka.http.javadsl.model.ws._
 import akka.http.javadsl.settings.{ ClientConnectionSettings, ConnectionPoolSettings, ServerSettings }
 import akka.japi.Pair
 import akka.actor.ActorSystem
-import akka.event.{ NoLogging, LoggingAdapterTest }
+import akka.event.NoLogging
 import akka.http.javadsl.model._
 import akka.http.scaladsl.TestUtils
 import akka.japi.Function
diff --git a/akka-http-testkit/build.sbt b/akka-http-testkit/build.sbt
index fa3003fbd6..f7bfd7a569 100644
--- a/akka-http-testkit/build.sbt
+++ b/akka-http-testkit/build.sbt
@@ -2,7 +2,6 @@ import akka._
 import com.typesafe.tools.mima.plugin.MimaKeys
 
 AkkaBuild.defaultSettings
-AkkaBuild.experimentalSettings
 Formatting.formatSettings
 OSGi.httpTestkit
 Dependencies.httpTestkit
diff --git a/akka-http-tests/build.sbt b/akka-http-tests/build.sbt
index 3efb382ca1..360d3e92d9 100644
--- a/akka-http-tests/build.sbt
+++ b/akka-http-tests/build.sbt
@@ -2,7 +2,6 @@ import akka._
 
 AkkaBuild.defaultSettings
 AkkaBuild.dontPublishSettings
-AkkaBuild.experimentalSettings
 Formatting.formatSettings
 Dependencies.httpTests
 
diff --git a/akka-persistence-shared/build.sbt b/akka-persistence-shared/build.sbt
new file mode 100644
index 0000000000..00f7448099
--- /dev/null
+++ b/akka-persistence-shared/build.sbt
@@ -0,0 +1,8 @@
+import akka._
+
+AkkaBuild.defaultSettings
+AkkaBuild.dontPublishSettings
+Formatting.formatSettings
+Dependencies.persistenceShared
+
+fork in Test := true
diff --git a/akka-persistence/src/test/scala/akka/persistence/journal/leveldb/PersistencePluginProxySpec.scala b/akka-persistence-shared/src/test/scala/akka/persistence/journal/leveldb/PersistencePluginProxySpec.scala
similarity index 100%
rename from akka-persistence/src/test/scala/akka/persistence/journal/leveldb/PersistencePluginProxySpec.scala
rename to akka-persistence-shared/src/test/scala/akka/persistence/journal/leveldb/PersistencePluginProxySpec.scala
diff --git a/akka-persistence/src/test/scala/akka/persistence/journal/leveldb/SharedLeveldbJournalSpec.scala b/akka-persistence-shared/src/test/scala/akka/persistence/journal/leveldb/SharedLeveldbJournalSpec.scala
similarity index 100%
rename from akka-persistence/src/test/scala/akka/persistence/journal/leveldb/SharedLeveldbJournalSpec.scala
rename to akka-persistence-shared/src/test/scala/akka/persistence/journal/leveldb/SharedLeveldbJournalSpec.scala
diff --git a/akka-persistence/src/test/scala/akka/persistence/serialization/SerializerSpec.scala b/akka-persistence-shared/src/test/scala/akka/persistence/serialization/SerializerSpec.scala
similarity index 100%
rename from akka-persistence/src/test/scala/akka/persistence/serialization/SerializerSpec.scala
rename to akka-persistence-shared/src/test/scala/akka/persistence/serialization/SerializerSpec.scala
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
index db15b8a1a4..3c8ca9ee12 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/FlowTest.java
@@ -100,23 +100,18 @@ public class FlowTest extends StreamTest {
   }
 
   @Test
-  public void mustBeAbleToUseStatefullMaponcat() throws Exception {
+  public void mustBeAbleToUseStatefulMaponcat() throws Exception {
     final JavaTestKit probe = new JavaTestKit(system);
     final java.lang.Iterable<Integer> input = Arrays.asList(1, 2, 3, 4, 5);
     final Source<Integer, NotUsed> ints = Source.from(input);
     final Flow<Integer, Integer, NotUsed> flow = Flow.of(Integer.class).statefulMapConcat(
-            new Creator<Function<Integer, Iterable<Integer>>>() {
-              public Function<Integer, Iterable<Integer>> create() {
-                int[] state = new int[1];
-                state[0] = 0;
-                return new Function<Integer, Iterable<Integer>>() {
-                  public List<Integer> apply(Integer elem) {
-                    List<Integer> list = new ArrayList<>(Collections.nCopies(state[0], elem));
-                    state[0] = elem;
-                    return list;
-                  }
-                };
-              }
+            () -> {
+              int[] state = new int[] {0};
+              return (elem) -> {
+                List<Integer> list = new ArrayList<>(Collections.nCopies(state[0], elem));
+                state[0] = elem;
+                return list;
+              };
             });
 
     ints.via(flow)
diff --git a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
index 06a553f180..0005cec746 100644
--- a/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
+++ b/akka-stream-tests/src/test/java/akka/stream/javadsl/SourceTest.java
@@ -501,6 +501,68 @@ public class SourceTest extends StreamTest {
     probe.expectMsgEquals(2);
   }
 
+  @Test
+  public void mustBeAbleToUseStatefulMaponcat() throws Exception {
+    final JavaTestKit probe = new JavaTestKit(system);
+    final java.lang.Iterable<Integer> input = Arrays.asList(1, 2, 3, 4, 5);
+    final Source<Integer, NotUsed> ints = Source.from(input).statefulMapConcat(
+            () -> {
+              int[] state = new int[] {0};
+              return (elem) -> {
+                List<Integer> list = new ArrayList<>(Collections.nCopies(state[0], elem));
+                state[0] = elem;
+                return list;
+              };
+            });
+
+    ints
+      .runFold("", (acc, elem) -> acc + elem, materializer)
+      .thenAccept(elem -> probe.getRef().tell(elem, ActorRef.noSender()));
+
+    probe.expectMsgEquals("2334445555");
+  }
+
+  @Test
+  public void mustBeAbleToUseIntersperse() throws Exception {
+    final JavaTestKit probe = new JavaTestKit(system);
+    final Source<String, NotUsed> source = Source.from(Arrays.asList("0", "1", "2", "3"))
+                                                 .intersperse("[", ",", "]");
+
+    final CompletionStage<Done> future =
+        source.runWith(Sink.foreach(elem -> probe.getRef().tell(elem, ActorRef.noSender())), materializer);
+
+    probe.expectMsgEquals("[");
+    probe.expectMsgEquals("0");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("1");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("2");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("3");
+    probe.expectMsgEquals("]");
+    future.toCompletableFuture().get(200, TimeUnit.MILLISECONDS);
+  }
+
+  @Test
+  public void mustBeAbleToUseIntersperseAndConcat() throws Exception {
+    final JavaTestKit probe = new JavaTestKit(system);
+    final Source<String, NotUsed> source = Source.from(Arrays.asList("0", "1", "2", "3"))
+                                                 .intersperse(",");
+
+    final CompletionStage<Done> future =
+        Source.single(">> ").concat(source).runWith(Sink.foreach(elem -> probe.getRef().tell(elem, ActorRef.noSender())), materializer);
+
+    probe.expectMsgEquals(">> ");
+    probe.expectMsgEquals("0");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("1");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("2");
+    probe.expectMsgEquals(",");
+    probe.expectMsgEquals("3");
+    future.toCompletableFuture().get(200, TimeUnit.MILLISECONDS);
+  }
+
   @Test
   public void mustBeAbleToUseDropWhile() throws Exception {
     final JavaTestKit probe = new JavaTestKit(system);
diff --git a/akka-stream/src/main/scala/akka/stream/impl/StreamLayout.scala b/akka-stream/src/main/scala/akka/stream/impl/StreamLayout.scala
index 4e4bf7393a..8252f3838c 100644
--- a/akka-stream/src/main/scala/akka/stream/impl/StreamLayout.scala
+++ b/akka-stream/src/main/scala/akka/stream/impl/StreamLayout.scala
@@ -362,12 +362,12 @@ object StreamLayout {
   }
 
   final case class CompositeModule(
-      override val subModules: Set[Module],
-      override val shape: Shape,
-      override val downstreams: Map[OutPort, InPort],
-      override val upstreams: Map[InPort, OutPort],
-      override val materializedValueComputation: MaterializedValueNode,
-      override val attributes: Attributes) extends Module {
+    override val subModules: Set[Module],
+    override val shape: Shape,
+    override val downstreams: Map[OutPort, InPort],
+    override val upstreams: Map[InPort, OutPort],
+    override val materializedValueComputation: MaterializedValueNode,
+    override val attributes: Attributes) extends Module {
 
     override def replaceShape(s: Shape): Module = {
       shape.requireSamePortsAs(s)
@@ -392,13 +392,13 @@ object StreamLayout {
   }
 
   final case class FusedModule(
-      override val subModules: Set[Module],
-      override val shape: Shape,
-      override val downstreams: Map[OutPort, InPort],
-      override val upstreams: Map[InPort, OutPort],
-      override val materializedValueComputation: MaterializedValueNode,
-      override val attributes: Attributes,
-      info: Fusing.StructuralInfo) extends Module {
+    override val subModules: Set[Module],
+    override val shape: Shape,
+    override val downstreams: Map[OutPort, InPort],
+    override val upstreams: Map[InPort, OutPort],
+    override val materializedValueComputation: MaterializedValueNode,
+    override val attributes: Attributes,
+    info: Fusing.StructuralInfo) extends Module {
 
     override def isFused: Boolean = true
 
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 1505ecd57d..f3bbcee4ed 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Flow.scala
@@ -289,34 +289,34 @@ final class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends
     new Flow(delegate.mapConcat { elem ⇒ Util.immutableSeq(f(elem)) })
 
   /**
-    * Transform each input element into an `Iterable` of output elements that is
-    * then flattened into the output stream. The transformation is meant to be stateful,
-    * which is enabled by creating the transformation function anew for every materialization —
-    * the returned function will typically close over mutable objects to store state between
-    * invocations. For the stateless variant see [[#mapConcat]].
-    *
-    * Make sure that the `Iterable` is immutable or at least not modified after
-    * being used as an output sequence. Otherwise the stream may fail with
-    * `ConcurrentModificationException` or other more subtle errors may occur.
-    *
-    * The returned `Iterable` MUST NOT contain `null` values,
-    * as they are illegal as stream elements - according to the Reactive Streams specification.
-    *
-    * '''Emits when''' the mapping function returns an element or there are still remaining elements
-    * from the previously calculated collection
-    *
-    * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
-    * previously calculated collection
-    *
-    * '''Completes when''' upstream completes and all remaining elements has been emitted
-    *
-    * '''Cancels when''' downstream cancels
-    */
-  def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]):javadsl.Flow[In, T, Mat] =
-    new Flow(delegate.statefulMapConcat{ () ⇒ {
+   * Transform each input element into an `Iterable` of output elements that is
+   * then flattened into the output stream. The transformation is meant to be stateful,
+   * which is enabled by creating the transformation function anew for every materialization —
+   * the returned function will typically close over mutable objects to store state between
+   * invocations. For the stateless variant see [[#mapConcat]].
+   *
+   * Make sure that the `Iterable` is immutable or at least not modified after
+   * being used as an output sequence. Otherwise the stream may fail with
+   * `ConcurrentModificationException` or other more subtle errors may occur.
+   *
+   * The returned `Iterable` MUST NOT contain `null` values,
+   * as they are illegal as stream elements - according to the Reactive Streams specification.
+   *
+   * '''Emits when''' the mapping function returns an element or there are still remaining elements
+   * from the previously calculated collection
+   *
+   * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
+   * previously calculated collection
+   *
+   * '''Completes when''' upstream completes and all remaining elements has been emitted
+   *
+   * '''Cancels when''' downstream cancels
+   */
+  def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]): javadsl.Flow[In, T, Mat] =
+    new Flow(delegate.statefulMapConcat { () ⇒
       val fun = f.create()
       elem ⇒ Util.immutableSeq(fun(elem))
-    }})
+    })
 
   /**
    * Transform this stream by applying the given function to each of the elements
@@ -762,23 +762,23 @@ final class Flow[-In, +Out, +Mat](delegate: scaladsl.Flow[In, Out, Mat]) extends
     new Flow(delegate.recover(pf))
 
   /**
-    * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
-    * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
-    * Source may be materialized.
-    *
-    * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
-    * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
-    *
-    * '''Emits when''' element is available from the upstream or upstream is failed and element is available
-    * from alternative Source
-    *
-    * '''Backpressures when''' downstream backpressures
-    *
-    * '''Completes when''' upstream completes or upstream failed with exception pf can handle
-    *
-    * '''Cancels when''' downstream cancels
-    *
-    */
+   * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
+   * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
+   * Source may be materialized.
+   *
+   * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
+   * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
+   *
+   * '''Emits when''' element is available from the upstream or upstream is failed and element is available
+   * from alternative Source
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' upstream completes or upstream failed with exception pf can handle
+   *
+   * '''Cancels when''' downstream cancels
+   *
+   */
   def recoverWith[T >: Out](pf: PartialFunction[Throwable, _ <: Graph[SourceShape[T], NotUsed]]): javadsl.Flow[In, T, Mat @uncheckedVariance] =
     new Flow(delegate.recoverWith(pf))
 
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 96fc23335a..178157febd 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/Source.scala
@@ -735,23 +735,23 @@ final class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Grap
     new Source(delegate.recover(pf))
 
   /**
-    * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
-    * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
-    * Source may be materialized.
-    *
-    * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
-    * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
-    *
-    * '''Emits when''' element is available from the upstream or upstream is failed and element is available
-    * from alternative Source
-    *
-    * '''Backpressures when''' downstream backpressures
-    *
-    * '''Completes when''' upstream completes or upstream failed with exception pf can handle
-    *
-    * '''Cancels when''' downstream cancels
-    *
-    */
+   * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
+   * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
+   * Source may be materialized.
+   *
+   * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
+   * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
+   *
+   * '''Emits when''' element is available from the upstream or upstream is failed and element is available
+   * from alternative Source
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' upstream completes or upstream failed with exception pf can handle
+   *
+   * '''Cancels when''' downstream cancels
+   *
+   */
   def recoverWith[T >: Out](pf: PartialFunction[Throwable, _ <: Graph[SourceShape[T], NotUsed]]): Source[T, Mat @uncheckedVariance] =
     new Source(delegate.recoverWith(pf))
 
@@ -777,38 +777,37 @@ final class Source[+Out, +Mat](delegate: scaladsl.Source[Out, Mat]) extends Grap
    * '''Cancels when''' downstream cancels
    */
   def mapConcat[T](f: function.Function[Out, _ <: java.lang.Iterable[T]]): javadsl.Source[T, Mat] =
-    new Source(delegate.statefulMapConcat(() ⇒ elem ⇒ Util.immutableSeq(f.apply(elem))))
-
+    new Source(delegate.mapConcat(elem ⇒ Util.immutableSeq(f.apply(elem))))
 
   /**
-    * Transform each input element into an `Iterable` of output elements that is
-    * then flattened into the output stream. The transformation is meant to be stateful,
-    * which is enabled by creating the transformation function anew for every materialization —
-    * the returned function will typically close over mutable objects to store state between
-    * invocations. For the stateless variant see [[#mapConcat]].
-    *
-    * Make sure that the `Iterable` is immutable or at least not modified after
-    * being used as an output sequence. Otherwise the stream may fail with
-    * `ConcurrentModificationException` or other more subtle errors may occur.
-    *
-    * The returned `Iterable` MUST NOT contain `null` values,
-    * as they are illegal as stream elements - according to the Reactive Streams specification.
-    *
-    * '''Emits when''' the mapping function returns an element or there are still remaining elements
-    * from the previously calculated collection
-    *
-    * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
-    * previously calculated collection
-    *
-    * '''Completes when''' upstream completes and all remaining elements has been emitted
-    *
-    * '''Cancels when''' downstream cancels
-    */
+   * Transform each input element into an `Iterable` of output elements that is
+   * then flattened into the output stream. The transformation is meant to be stateful,
+   * which is enabled by creating the transformation function anew for every materialization —
+   * the returned function will typically close over mutable objects to store state between
+   * invocations. For the stateless variant see [[#mapConcat]].
+   *
+   * Make sure that the `Iterable` is immutable or at least not modified after
+   * being used as an output sequence. Otherwise the stream may fail with
+   * `ConcurrentModificationException` or other more subtle errors may occur.
+   *
+   * The returned `Iterable` MUST NOT contain `null` values,
+   * as they are illegal as stream elements - according to the Reactive Streams specification.
+   *
+   * '''Emits when''' the mapping function returns an element or there are still remaining elements
+   * from the previously calculated collection
+   *
+   * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
+   * previously calculated collection
+   *
+   * '''Completes when''' upstream completes and all remaining elements has been emitted
+   *
+   * '''Cancels when''' downstream cancels
+   */
   def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]): javadsl.Source[T, Mat] =
-    new Source(delegate.statefulMapConcat{ () ⇒ {
+    new Source(delegate.statefulMapConcat { () ⇒
       val fun = f.create()
       elem ⇒ Util.immutableSeq(fun(elem))
-    }})
+    })
 
   /**
    * Transform this stream by applying the given function to each of the elements
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala b/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
index 3d9236b10b..26ea46a27a 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/SubFlow.scala
@@ -140,38 +140,37 @@ class SubFlow[-In, +Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Flo
    * '''Cancels when''' downstream cancels
    */
   def mapConcat[T](f: function.Function[Out, java.lang.Iterable[T]]): SubFlow[In, T, Mat] =
-    new SubFlow(delegate.statefulMapConcat { () ⇒ elem ⇒ Util.immutableSeq(f(elem)) })
+    new SubFlow(delegate.mapConcat { elem ⇒ Util.immutableSeq(f(elem)) })
 
   /**
-    * Transform each input element into an `Iterable` of output elements that is
-    * then flattened into the output stream. The transformation is meant to be stateful,
-    * which is enabled by creating the transformation function anew for every materialization —
-    * the returned function will typically close over mutable objects to store state between
-    * invocations. For the stateless variant see [[#mapConcat]].
-    *
-    * Make sure that the `Iterable` is immutable or at least not modified after
-    * being used as an output sequence. Otherwise the stream may fail with
-    * `ConcurrentModificationException` or other more subtle errors may occur.
-    *
-    * The returned `Iterable` MUST NOT contain `null` values,
-    * as they are illegal as stream elements - according to the Reactive Streams specification.
-    *
-    * '''Emits when''' the mapping function returns an element or there are still remaining elements
-    * from the previously calculated collection
-    *
-    * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
-    * previously calculated collection
-    *
-    * '''Completes when''' upstream completes and all remaining elements has been emitted
-    *
-    * '''Cancels when''' downstream cancels
-    */
+   * Transform each input element into an `Iterable` of output elements that is
+   * then flattened into the output stream. The transformation is meant to be stateful,
+   * which is enabled by creating the transformation function anew for every materialization —
+   * the returned function will typically close over mutable objects to store state between
+   * invocations. For the stateless variant see [[#mapConcat]].
+   *
+   * Make sure that the `Iterable` is immutable or at least not modified after
+   * being used as an output sequence. Otherwise the stream may fail with
+   * `ConcurrentModificationException` or other more subtle errors may occur.
+   *
+   * The returned `Iterable` MUST NOT contain `null` values,
+   * as they are illegal as stream elements - according to the Reactive Streams specification.
+   *
+   * '''Emits when''' the mapping function returns an element or there are still remaining elements
+   * from the previously calculated collection
+   *
+   * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
+   * previously calculated collection
+   *
+   * '''Completes when''' upstream completes and all remaining elements has been emitted
+   *
+   * '''Cancels when''' downstream cancels
+   */
   def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]): SubFlow[In, T, Mat] =
-    new SubFlow(delegate.statefulMapConcat{ () ⇒ {
+    new SubFlow(delegate.statefulMapConcat { () ⇒
       val fun = f.create()
       elem ⇒ Util.immutableSeq(fun(elem))
-    }})
-
+    })
 
   /**
    * Transform this stream by applying the given function to each of the elements
@@ -615,23 +614,23 @@ class SubFlow[-In, +Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Flo
     new SubFlow(delegate.recover(pf))
 
   /**
-    * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
-    * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
-    * Source may be materialized.
-    *
-    * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
-    * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
-    *
-    * '''Emits when''' element is available from the upstream or upstream is failed and element is available
-    * from alternative Source
-    *
-    * '''Backpressures when''' downstream backpressures
-    *
-    * '''Completes when''' upstream completes or upstream failed with exception pf can handle
-    *
-    * '''Cancels when''' downstream cancels
-    *
-    */
+   * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
+   * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
+   * Source may be materialized.
+   *
+   * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
+   * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
+   *
+   * '''Emits when''' element is available from the upstream or upstream is failed and element is available
+   * from alternative Source
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' upstream completes or upstream failed with exception pf can handle
+   *
+   * '''Cancels when''' downstream cancels
+   *
+   */
   def recoverWith[T >: Out](pf: PartialFunction[Throwable, _ <: Graph[SourceShape[T], NotUsed]]): SubFlow[In, T, Mat @uncheckedVariance] =
     new SubFlow(delegate.recoverWith(pf))
 
diff --git a/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala b/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
index ae682fcb45..96b8dce5b2 100644
--- a/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
+++ b/akka-stream/src/main/scala/akka/stream/javadsl/SubSource.scala
@@ -138,37 +138,37 @@ class SubSource[+Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Source
    * '''Cancels when''' downstream cancels
    */
   def mapConcat[T](f: function.Function[Out, java.lang.Iterable[T]]): SubSource[T, Mat] =
-    new SubSource(delegate.statefulMapConcat { () ⇒ elem ⇒ Util.immutableSeq(f(elem)) })
+    new SubSource(delegate.mapConcat { elem ⇒ Util.immutableSeq(f(elem)) })
 
   /**
-    * Transform each input element into an `Iterable` of output elements that is
-    * then flattened into the output stream. The transformation is meant to be stateful,
-    * which is enabled by creating the transformation function anew for every materialization —
-    * the returned function will typically close over mutable objects to store state between
-    * invocations. For the stateless variant see [[#mapConcat]].
-    *
-    * Make sure that the `Iterable` is immutable or at least not modified after
-    * being used as an output sequence. Otherwise the stream may fail with
-    * `ConcurrentModificationException` or other more subtle errors may occur.
-    *
-    * The returned `Iterable` MUST NOT contain `null` values,
-    * as they are illegal as stream elements - according to the Reactive Streams specification.
-    *
-    * '''Emits when''' the mapping function returns an element or there are still remaining elements
-    * from the previously calculated collection
-    *
-    * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
-    * previously calculated collection
-    *
-    * '''Completes when''' upstream completes and all remaining elements has been emitted
-    *
-    * '''Cancels when''' downstream cancels
-    */
-  def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]):SubSource[T, Mat] =
-    new SubSource(delegate.statefulMapConcat{ () ⇒ {
+   * Transform each input element into an `Iterable` of output elements that is
+   * then flattened into the output stream. The transformation is meant to be stateful,
+   * which is enabled by creating the transformation function anew for every materialization —
+   * the returned function will typically close over mutable objects to store state between
+   * invocations. For the stateless variant see [[#mapConcat]].
+   *
+   * Make sure that the `Iterable` is immutable or at least not modified after
+   * being used as an output sequence. Otherwise the stream may fail with
+   * `ConcurrentModificationException` or other more subtle errors may occur.
+   *
+   * The returned `Iterable` MUST NOT contain `null` values,
+   * as they are illegal as stream elements - according to the Reactive Streams specification.
+   *
+   * '''Emits when''' the mapping function returns an element or there are still remaining elements
+   * from the previously calculated collection
+   *
+   * '''Backpressures when''' downstream backpressures or there are still remaining elements from the
+   * previously calculated collection
+   *
+   * '''Completes when''' upstream completes and all remaining elements has been emitted
+   *
+   * '''Cancels when''' downstream cancels
+   */
+  def statefulMapConcat[T](f: function.Creator[function.Function[Out, java.lang.Iterable[T]]]): SubSource[T, Mat] =
+    new SubSource(delegate.statefulMapConcat { () ⇒
       val fun = f.create()
       elem ⇒ Util.immutableSeq(fun(elem))
-    }})
+    })
 
   /**
    * Transform this stream by applying the given function to each of the elements
@@ -612,23 +612,23 @@ class SubSource[+Out, +Mat](delegate: scaladsl.SubFlow[Out, Mat, scaladsl.Source
     new SubSource(delegate.recover(pf))
 
   /**
-    * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
-    * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
-    * Source may be materialized.
-    *
-    * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
-    * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
-    *
-    * '''Emits when''' element is available from the upstream or upstream is failed and element is available
-    * from alternative Source
-    *
-    * '''Backpressures when''' downstream backpressures
-    *
-    * '''Completes when''' upstream completes or upstream failed with exception pf can handle
-    *
-    * '''Cancels when''' downstream cancels
-    *
-    */
+   * RecoverWith allows to switch to alternative Source on flow failure. It will stay in effect after
+   * a failure has been recovered so that each time there is a failure it is fed into the `pf` and a new
+   * Source may be materialized.
+   *
+   * Since the underlying failure signal onError arrives out-of-band, it might jump over existing elements.
+   * This stage can recover the failure signal, but not the skipped elements, which will be dropped.
+   *
+   * '''Emits when''' element is available from the upstream or upstream is failed and element is available
+   * from alternative Source
+   *
+   * '''Backpressures when''' downstream backpressures
+   *
+   * '''Completes when''' upstream completes or upstream failed with exception pf can handle
+   *
+   * '''Cancels when''' downstream cancels
+   *
+   */
   def recoverWith[T >: Out](pf: PartialFunction[Throwable, _ <: Graph[SourceShape[T], NotUsed]]): SubSource[T, Mat @uncheckedVariance] =
     new SubSource(delegate.recoverWith(pf))
 
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 01b61eb14e..b94777b096 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Graph.scala
@@ -471,7 +471,7 @@ final class Broadcast[T](private val outputPorts: Int, eagerCancel: Boolean) ext
 
 object Partition {
 
-  case class PartitionOutOfBoundsException(msg:String) extends RuntimeException(msg) with NoStackTrace
+  case class PartitionOutOfBoundsException(msg: String) extends IndexOutOfBoundsException(msg) with NoStackTrace
 
   /**
    * Create a new `Partition` stage with the specified input type.
@@ -1009,7 +1009,7 @@ object GraphDSL extends GraphApply {
     }
 
     private class PortOpsImpl[+Out](override val outlet: Outlet[Out @uncheckedVariance], b: Builder[_])
-      extends PortOps[Out] {
+        extends PortOps[Out] {
 
       override def withAttributes(attr: Attributes): Repr[Out] = throw settingAttrNotSupported
       override def addAttributes(attr: Attributes): Repr[Out] = throw settingAttrNotSupported
@@ -1019,7 +1019,6 @@ object GraphDSL extends GraphApply {
       private def settingAttrNotSupported =
         new UnsupportedOperationException("Cannot set attributes on chained ops from a junction output port")
 
-
       override def importAndGetPort(b: Builder[_]): Outlet[Out @uncheckedVariance] = outlet
 
       override def via[T, Mat2](flow: Graph[FlowShape[Out, T], Mat2]): Repr[T] =
diff --git a/project/AkkaBuild.scala b/project/AkkaBuild.scala
index 84ecfb4f69..df1358a253 100644
--- a/project/AkkaBuild.scala
+++ b/project/AkkaBuild.scala
@@ -55,7 +55,8 @@ object AkkaBuild extends Build {
     ),
     aggregate = Seq(actor, testkit, actorTests, remote, remoteTests, camel,
       cluster, clusterMetrics, clusterTools, clusterSharding, distributedData,
-      slf4j, agent, persistence, persistenceQuery, persistenceTck, kernel, osgi, docs, contrib, samples, multiNodeTestkit, benchJmh, typed, protobuf,
+      slf4j, agent, persistence, persistenceQuery, persistenceTck, persistenceShared,
+      kernel, osgi, docs, contrib, samples, multiNodeTestkit, benchJmh, typed, protobuf,
       stream, streamTestkit, streamTests, streamTestsTck, parsing,
       httpCore, http, httpSprayJson, httpXml, httpJackson, httpTests, httpTestkit
     )
@@ -68,7 +69,8 @@ object AkkaBuild extends Build {
     // samples don't work with dbuild right now
     aggregate = Seq(actor, testkit, actorTests, remote, remoteTests, camel,
       cluster, clusterMetrics, clusterTools, clusterSharding, distributedData,
-      slf4j, persistence, persistenceQuery, persistenceTck, kernel, osgi, contrib, multiNodeTestkit, benchJmh, typed, protobuf,
+      slf4j, persistence, persistenceQuery, persistenceTck, persistenceShared,
+      kernel, osgi, contrib, multiNodeTestkit, benchJmh, typed, protobuf,
       stream, streamTestkit, streamTests, streamTestsTck, parsing,
       httpCore, http, httpSprayJson, httpXml, httpJackson, httpTests, httpTestkit
     )
@@ -181,7 +183,7 @@ object AkkaBuild extends Build {
   lazy val persistence = Project(
     id = "akka-persistence",
     base = file("akka-persistence"),
-    dependencies = Seq(actor, remote % "test->test", testkit % "test->test", protobuf)
+    dependencies = Seq(actor, testkit % "test->test", protobuf)
   )
 
   lazy val persistenceQuery = Project(
@@ -200,6 +202,12 @@ object AkkaBuild extends Build {
     dependencies = Seq(persistence % "compile;provided->provided;test->test", testkit % "compile;test->test")
   )
 
+  lazy val persistenceShared = Project(
+    id = "akka-persistence-shared",
+    base = file("akka-persistence-shared"),
+    dependencies = Seq(persistence % "test->test", testkit % "test->test", remote % "test", protobuf)
+  )
+
   lazy val httpCore = Project(
     id = "akka-http-core",
     base = file("akka-http-core"),
@@ -213,13 +221,13 @@ object AkkaBuild extends Build {
   )
 
   lazy val httpTestkit = Project(
-    id = "akka-http-testkit-experimental",
+    id = "akka-http-testkit",
     base = file("akka-http-testkit"),
     dependencies = Seq(http, streamTestkit)
   )
 
   lazy val httpTests = Project(
-    id = "akka-http-tests-experimental",
+    id = "akka-http-tests",
     base = file("akka-http-tests"),
     dependencies = Seq(httpTestkit % "test", httpSprayJson, httpXml, httpJackson)
   )
@@ -272,8 +280,8 @@ object AkkaBuild extends Build {
 
   lazy val streamTestkit = Project(
     id = "akka-stream-testkit",
-    base = file("akka-stream-testkit"), // TODO that persistence dependency
-    dependencies = Seq(stream, persistence % "compile;provided->provided;test->test", testkit % "compile;test->test")
+    base = file("akka-stream-testkit"),
+    dependencies = Seq(stream, testkit % "compile;test->test")
   )
 
   lazy val streamTests = Project(
diff --git a/project/Dependencies.scala b/project/Dependencies.scala
index ae88f434e3..9555a7001f 100644
--- a/project/Dependencies.scala
+++ b/project/Dependencies.scala
@@ -140,12 +140,14 @@ object Dependencies {
 
   val agent = l ++= Seq(scalaStm.value, Test.scalatest.value, Test.junit)
 
-  val persistence = l ++= Seq(Provided.levelDB, Provided.levelDBNative, Test.scalatest.value, Test.junit, Test.commonsIo, Test.scalaXml)
+  val persistence = l ++= Seq(Provided.levelDB, Provided.levelDBNative, Test.scalatest.value, Test.junit, Test.commonsIo, Test.commonsCodec, Test.scalaXml)
 
   val persistenceQuery = l ++= Seq(Test.scalatest.value, Test.junit, Test.commonsIo)
 
   val persistenceTck = l ++= Seq(Test.scalatest.value.copy(configurations = Some("compile")), Test.junit.copy(configurations = Some("compile")))
 
+  val persistenceShared = l ++= Seq(Provided.levelDB, Provided.levelDBNative)
+
   val kernel = l ++= Seq(Test.scalatest.value, Test.junit)
 
   val camel = l ++= Seq(camelCore, Test.scalatest.value, Test.junit, Test.mockito, Test.logback, Test.commonsIo, Test.junitIntf)