HADOOP-19221. mockito regression

Mockito test failed because mockito tests are so brittle.

Change-Id: Ia5e8a4fdb74b08a04af58f3b5c868392758cf9f3

Author: steveloughran

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/troubleshooting_s3a.md

@@ -579,7 +579,7 @@ Retrying _should_ make it go away.
 The 500 error is considered retryable by the AWS SDK, which will have already
 tried it `fs.s3a.attempts.maximum` times before reaching the S3A client -which
 will also retry.
- 
+
 The S3A client will attempt to retry on a 500 (or other 5xx error other than 501/503)
 if the option `fs.s3a.retry.http.5xx.errors` is set to `true`.
 This is the default.

hadoop-tools/hadoop-aws/src/test/java/org/apache/hadoop/fs/s3a/TestS3ABlockOutputStream.java

@@ -87,7 +87,7 @@ public void setUp() throws Exception {
 
   @Test
   public void testFlushNoOpWhenStreamClosed() throws Exception {
-    doThrow(new IOException()).when(stream).checkOpen();
+    doThrow(new StreamClosedException()).when(stream).checkOpen();
 
     stream.flush();
   }
@@ -115,7 +115,12 @@ public void testWriteOperationHelperPartLimits() throws Throwable {
             "uploadId", 50000, 1024));
   }
 
-  static class StreamClosedException extends IOException {}
+  static class StreamClosedException extends ClosedIOException {
+
+    StreamClosedException() {
+      super("path", "message");
+    }
+  }
 
   @Test
   public void testStreamClosedAfterAbort() throws Exception {