From 033516b188988c34f41685b0e545893b1a71ebcf Mon Sep 17 00:00:00 2001
From: Adam Warski <adam@warski.org>
Date: Mon, 8 Aug 2016 07:11:59 -0700
Subject: [PATCH] Adding ScalaDocs for FlowOps.async #21137

---
 .../src/main/scala/akka/stream/scaladsl/Flow.scala        | 8 ++++++++
 1 file changed, 8 insertions(+)

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 de991e41a1..e5783aadd2 100644
--- a/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
+++ b/akka-stream/src/main/scala/akka/stream/scaladsl/Flow.scala
@@ -1825,6 +1825,14 @@ trait FlowOps[+Out, +Mat] {
 
   def named(name: String): Repr[Out]
 
+  /**
+   * Put an asynchronous boundary around this `Flow`.
+   * 
+   * If this is a `SubFlow` (created e.g. by `groupBy`), this creates an
+   * asynchronous boundary around each materialized sub-flow, not the
+   * super-flow. That way, the super-flow will communicate with sub-flows
+   * asynchronously.
+   */
   def async: Repr[Out]
 
   /** INTERNAL API */