HDDS-456. TestOzoneShell#init is breaking due to Null Pointer Exception. Contributed by Dinesh Chitlangia.

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/OzoneManager.java

@@ -305,6 +305,9 @@ public final class OzoneManager extends ServiceRuntimeInfoImpl
       terminate(0);
       return null;
     default:
+      if (argv == null) {
+        argv = new String[]{};
+      }
       StringUtils.startupShutdownMessage(OzoneManager.class, argv, LOG);
       return new OzoneManager(conf);
     }