MAPREDUCE-6855. Specify charset when create String in CredentialsTestJob. Contributed by Kai Sasaki.

(cherry picked from commit 14413989cac9acc1fa6f8d330fac32f772613325)
(cherry picked from commit aa1f944bba02dcb9a14d9d37cfc113845d437ffa)

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-jobclient/src/test/java/org/apache/hadoop/mapreduce/security/CredentialsTestJob.java

@@ -19,6 +19,7 @@
 package org.apache.hadoop.mapreduce.security;
 
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 
 
 import org.apache.hadoop.conf.Configuration;
@@ -64,7 +65,7 @@ public class CredentialsTestJob extends Configured implements Tool {
         // fail the test
       }
 
-      String secretValueStr = new String (secretValue);
+      String secretValueStr = new String (secretValue, StandardCharsets.UTF_8);
       System.out.println(secretValueStr);
 
       if  ( !("password"+i).equals(secretValueStr)){