hg: jdk/sandbox: 8231161: Wrong return type in code sample in Collector API documentation

[chris.hegarty at oracle.com]

Changeset: e25b317d0350
Author:    jboes
Date:      2019-10-03 18:59 +0100
URL:       https://hg.openjdk.java.net/jdk/sandbox/rev/e25b317d0350

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