HDDS-2078. Get/Renew DelegationToken NPE after HDDS-1909

Closes #1444

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/security/OMGetDelegationTokenRequest.java

@@ -147,8 +147,8 @@ public class OMGetDelegationTokenRequest extends OMClientRequest {
     OMMetadataManager omMetadataManager = ozoneManager.getMetadataManager();
 
     try {
-      OzoneTokenIdentifier ozoneTokenIdentifier =
-          ozoneTokenIdentifierToken.decodeIdentifier();
+      OzoneTokenIdentifier ozoneTokenIdentifier = OzoneTokenIdentifier.
+          readProtoBuf(ozoneTokenIdentifierToken.getIdentifier());
 
       // Update in memory map of token.
       long renewTime = ozoneManager.getDelegationTokenMgr()

hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/om/request/security/OMRenewDelegationTokenRequest.java

@@ -123,8 +123,8 @@ public class OMRenewDelegationTokenRequest extends OMClientRequest {
             .setSuccess(true);
     try {
 
-      OzoneTokenIdentifier ozoneTokenIdentifier =
-          ozoneTokenIdentifierToken.decodeIdentifier();
+      OzoneTokenIdentifier ozoneTokenIdentifier = OzoneTokenIdentifier.
+          readProtoBuf(ozoneTokenIdentifierToken.getIdentifier());
 
       // Update in memory map of token.
       ozoneManager.getDelegationTokenMgr()