#22903 Fix code snippeds

* move scala and java sources out of paradox sources
* replace relative paths with $code$ and $akka$
* fix broken includes

akka-docs/src/main/scala/docs/stream/cookbook/RecipeDigest.scala

@@ -0,0 +1,72 @@
+package docs.stream.cookbook
+
+import java.security.MessageDigest
+
+import akka.NotUsed
+import akka.stream.{ Attributes, Outlet, Inlet, FlowShape }
+import akka.stream.scaladsl.{ Sink, Source }
+import akka.util.ByteString
+
+import scala.concurrent.Await
+import scala.concurrent.duration._
+
+class RecipeDigest extends RecipeSpec {
+
+  "Recipe for calculating digest" must {
+
+    "work" in {
+
+      val data = Source(List(
+        ByteString("abcdbcdecdef"),
+        ByteString("defgefghfghighijhijkijkljklmklmnlmnomnopnopq")))
+
+      //#calculating-digest
+      import akka.stream.stage._
+      class DigestCalculator(algorithm: String) extends GraphStage[FlowShape[ByteString, ByteString]] {
+        val in = Inlet[ByteString]("DigestCalculator.in")
+        val out = Outlet[ByteString]("DigestCalculator.out")
+        override val shape = FlowShape.of(in, out)
+
+        override def createLogic(inheritedAttributes: Attributes): GraphStageLogic = new GraphStageLogic(shape) {
+          val digest = MessageDigest.getInstance(algorithm)
+
+          setHandler(out, new OutHandler {
+            override def onPull(): Trigger = {
+              pull(in)
+            }
+          })
+
+          setHandler(in, new InHandler {
+            override def onPush(): Trigger = {
+              val chunk = grab(in)
+              digest.update(chunk.toArray)
+              pull(in)
+            }
+
+            override def onUpstreamFinish(): Unit = {
+              emit(out, ByteString(digest.digest()))
+              completeStage()
+            }
+          })
+
+        }
+      }
+      val digest: Source[ByteString, NotUsed] = data.via(new DigestCalculator("SHA-256"))
+      //#calculating-digest
+
+      Await.result(digest.runWith(Sink.head), 3.seconds) should be(
+        ByteString(
+          0x24, 0x8d, 0x6a, 0x61,
+          0xd2, 0x06, 0x38, 0xb8,
+          0xe5, 0xc0, 0x26, 0x93,
+          0x0c, 0x3e, 0x60, 0x39,
+          0xa3, 0x3c, 0xe4, 0x59,
+          0x64, 0xff, 0x21, 0x67,
+          0xf6, 0xec, 0xed, 0xd4,
+          0x19, 0xdb, 0x06, 0xc1))
+
+    }
+
+  }
+
+}