git: openjdk/mobile: 8231161: Wrong return type in code sample in Collector API documentation

[duke]

Changeset: 4dafa303
Author:    Julia Boes <jboes at openjdk.org>
Date:      2019-10-03 18:59:56 +0000
URL:       https://git.openjdk.java.net/mobile/commit/4dafa303

8231161: Wrong return type in code sample in Collector API documentation

Correct declaration of container from R to A and add compilation test

Reviewed-by: smarks, lancea

! src/java.base/share/classes/java/util/stream/Collector.java
+ test/jdk/java/util/stream/test/org/openjdk/tests/java/util/stream/CollectorExample.java