HDFS-12828. OIV ReverseXML Processor fails with escaped characters

Signed-off-by: Akira Ajisaka <aajisaka@apache.org>
(cherry picked from commit 2d9e791a9073de9f65fef5407efd3a42894bc97f)
(cherry picked from commit 8f341c673f4db981544faba79d0c20bfe9c3fd99)

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/OfflineImageReconstructor.java

@@ -380,8 +380,8 @@ class OfflineImageReconstructor {
           break;
         case XMLEvent.CHARACTERS:
           String val = XMLUtils.
-              unmangleXmlString(ev.asCharacters().getData(), true);
-          parent.setVal(val);
+              unmangleXmlString(ev.asCharacters().getData(), false);
+          parent.setVal(parent.getVal() + val);
           events.nextEvent();
           break;
         case XMLEvent.ATTRIBUTE:

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/tools/offlineImageViewer/TestOfflineImageViewer.java

@@ -153,10 +153,15 @@ public class TestOfflineImageViewer {
       dirCount++;
       writtenFiles.put(emptydir.toString(), hdfs.getFileStatus(emptydir));
 
-      //Create a directory whose name should be escaped in XML
+      //Create directories whose name should be escaped in XML
       Path invalidXMLDir = new Path("/dirContainingInvalidXMLChar\u0000here");
       hdfs.mkdirs(invalidXMLDir);
       dirCount++;
+      Path entityRefXMLDir = new Path("/dirContainingEntityRef&here");
+      hdfs.mkdirs(entityRefXMLDir);
+      dirCount++;
+      writtenFiles.put(entityRefXMLDir.toString(),
+          hdfs.getFileStatus(entityRefXMLDir));
 
       //Create a directory with sticky bits
       Path stickyBitDir = new Path("/stickyBit");