HDFS-12554. Ozone: Fix TestDatanodeStateMachine#testDatanodeStateMachineWithInvalidConfiguration. Contributed by Ajay Kumar.

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/ozone/web/utils/OzoneUtils.java

@@ -270,7 +270,7 @@ public final class OzoneUtils {
    */
   public static String getDatanodeIDPath(Configuration conf) {
     String dataNodeIDPath = conf.get(ScmConfigKeys.OZONE_SCM_DATANODE_ID);
-    if (Strings.isNullOrEmpty(dataNodeIDPath)) {
+    if (dataNodeIDPath == null) {
       String metaPath = conf.get(OzoneConfigKeys.OZONE_METADATA_DIRS);
       if (Strings.isNullOrEmpty(metaPath)) {
         // this means meta data is not found, in theory should not happen at

hadoop-hdfs-project/hadoop-hdfs/src/site/markdown/OzoneGettingStarted.md.vm

@@ -139,9 +139,9 @@ place  and not mingled with HDFS settings.
 ```
 
 * _*ozone.scm.datanode.id*_ Each datanode that speaks to SCM generates an ID
-just like HDFS. This ID is stored is a location pointed by this setting. If
-this setting is not valid, datanodes will fail to come up. Please note:
-This path that is will created by datanodes to store the datanode ID. Here is an example,
+just like HDFS.  This is an optional setting. Please note:
+This path will be created by datanodes if it doesn't exist already. Here is an
+ example,
 
 ```
    <property>