@Test
public void testNamingPeriods() {

  PrometheusMetricsSink sink = new PrometheusMetricsSink();
  String recordName = "org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl";
  String metricName = "DfsUsed";
  Assert.assertEquals(
      "org_apache_hadoop_hdfs_server_datanode_fsdataset_impl_fs_dataset_impl_dfs_used",
      sink.prometheusName(recordName, metricName));
}