Clarify log message

Author: Ben Roling

hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/impl/ChangeTracker.java

@@ -54,7 +54,7 @@ public class ChangeTracker {
   private static final Logger LOG =
       LoggerFactory.getLogger(ChangeTracker.class);
 
-  public static final String CHANGE_REPORTED_BY_S3 = "reported by S3";
+  public static final String CHANGE_REPORTED_BY_S3 = "Change reported by S3";
 
   /** Policy to use. */
   private final ChangeDetectionPolicy policy;
@@ -164,13 +164,12 @@ public void processResponse(final S3Object object,
         // object was not returned.
         versionMismatches.incrementAndGet();
         throw new RemoteFileChangedException(uri, operation,
-            String.format("%s change "
-                    + CHANGE_REPORTED_BY_S3
+            String.format(CHANGE_REPORTED_BY_S3
                     + " while reading"
                     + " at position %s."
-                    + " Version %s was unavailable",
-                getSource(),
+                    + " %s %s was unavailable",
                 pos,
+                getSource(),
                 getRevisionId()));
       } else {
         throw new PathIOException(uri, "No data returned from GET request");

hadoop-tools/hadoop-aws/src/site/markdown/tools/hadoop-aws/s3guard.md

@@ -1136,8 +1136,8 @@ the file.
 
 ```
 org.apache.hadoop.fs.s3a.RemoteFileChangedException: open 's3a://my-bucket/test/file.txt':
-  ETag change reported by S3 while reading at position 0.
-  Version 4e886e26c072fef250cfaf8037675405 was unavailable
+  Change reported by S3 while reading at position 0.
+  ETag 4e886e26c072fef250cfaf8037675405 was unavailable
   at org.apache.hadoop.fs.s3a.impl.ChangeTracker.processResponse(ChangeTracker.java:167)
   at org.apache.hadoop.fs.s3a.S3AInputStream.reopen(S3AInputStream.java:207)
   at org.apache.hadoop.fs.s3a.S3AInputStream.lambda$lazySeek$1(S3AInputStream.java:355)

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

@@ -970,8 +970,8 @@ and the like. The standard strategy here is to save to HDFS and then copy to S3.
 
 ```
 org.apache.hadoop.fs.s3a.RemoteFileChangedException: re-open `s3a://my-bucket/test/file.txt':
-  ETag change reported by S3 while reading at position 1949.
-  Version f9c186d787d4de9657e99f280ba26555 was unavailable
+  Change reported by S3 while reading at position 1949.
+  ETag f9c186d787d4de9657e99f280ba26555 was unavailable
   at org.apache.hadoop.fs.s3a.impl.ChangeTracker.processResponse(ChangeTracker.java:137)
   at org.apache.hadoop.fs.s3a.S3AInputStream.reopen(S3AInputStream.java:200)
   at org.apache.hadoop.fs.s3a.S3AInputStream.lambda$lazySeek$1(S3AInputStream.java:346)