Fix TestStartSecureDataNode.

Change-Id: I14028f6acc5cd95257bbdfab44357ec35f763819

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/TestStartSecureDataNode.java

@@ -28,6 +28,7 @@ import org.apache.hadoop.hdfs.MiniDFSCluster;
 import static org.apache.hadoop.security.SecurityUtilTestHelper.isExternalKdcRunning;
 import org.apache.hadoop.net.NetUtils;
 import org.junit.Rule;
+import org.junit.jupiter.api.Assumptions;
 import org.junit.jupiter.api.Test;
 import org.junit.rules.ExpectedException;
 import java.net.BindException;
@@ -58,7 +59,7 @@ public class TestStartSecureDataNode {
 
   private void testExternalKdcRunning() {
     // Tests are skipped if external KDC is not running.
-    Assume.assumeTrue(isExternalKdcRunning());
+    Assumptions.assumeTrue(isExternalKdcRunning());
   }
 
   @Test