HADOOP-19430. Upgrade JUnit from 4 to 5 in hadoop-datajoin. (#7618)

Co-authored-by: Chris Nauroth <cnauroth@apache.org>
Co-authored-by: Hualong Zhang <hualong.z@hotmail.com>
Reviewed-by: Chris Nauroth <cnauroth@apache.org>
Reviewed-by: Hualong Zhang <hualong.z@hotmail.com>
Signed-off-by: Shilun Fan <slfan1989@apache.org>

hadoop-tools/hadoop-datajoin/src/test/java/org/apache/hadoop/contrib/utils/join/TestDataJoin.java

@@ -20,10 +20,11 @@ package org.apache.hadoop.contrib.utils.join;
 
 import java.io.IOException;
 
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
-import static org.junit.Assert.*;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.hdfs.MiniDFSCluster;
@@ -43,13 +44,13 @@ import org.apache.hadoop.mapred.*;
 public class TestDataJoin {
   private static MiniDFSCluster cluster = null;
 
-  @Before
+  @BeforeEach
   public void setUp() throws Exception {
     Configuration conf = new Configuration();
     cluster = new MiniDFSCluster.Builder(conf).numDataNodes(2).build();
   }
 
-  @After
+  @AfterEach
   public void tearDown() throws Exception {
     if (cluster != null) {
       cluster.shutdown();