fix checkstyle.

Author: hfutatzhanghb

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

@@ -835,7 +835,8 @@ public boolean mockCongestedForTest() {
         }
       });
       PipelineAck.ECN ecn = cluster.getDataNodes().get(0).getECN();
-      MetricsRecordBuilder dnMetrics = getMetrics(cluster.getDataNodes().get(0).getMetrics().name());
+      MetricsRecordBuilder dnMetrics = getMetrics(cluster.getDataNodes().get(0)
+          .getMetrics().name());
       Assert.assertEquals(1L, getLongCounter("CongestedCount", dnMetrics));
     } finally {
       if (cluster != null) {