[SPARK-3369][CORE][STREAMING] Java mapPartitions Iterator->Iterable is inconsistent with Scala's Iterator->Iterator

Fix Java function API methods for flatMap and mapPartitions to require producing only an Iterator, not Iterable. Also fix DStream.flatMap to require a function producing TraversableOnce only, not Traversable.

CC rxin pwendell for API change; tdas since it also touches streaming.

Author: Sean Owen <sowen@cloudera.com>

Closes #10413 from srowen/SPARK-3369.

1 files changed, 2 insertions, 2 deletions

diff --git a/docs/streaming-programming-guide.md b/docs/streaming-programming-guide.md
index 93c34efb66..7e681b67cf 100644
--- a/docs/streaming-programming-guide.md
+++ b/docs/streaming-programming-guide.md
@@ -165,8 +165,8 @@ space into words.
 // Split each line into words
 JavaDStream<String> words = lines.flatMap(
   new FlatMapFunction<String, String>() {
-    @Override public Iterable<String> call(String x) {
-      return Arrays.asList(x.split(" "));
+    @Override public Iterator<String> call(String x) {
+      return Arrays.asList(x.split(" ")).iterator();
     }
   });
 {% endhighlight %}