diff --git a/src/main/java/org/gcube/accounting/datamodel/RawUsageRecord.java b/src/main/java/org/gcube/accounting/datamodel/RawUsageRecord.java
index 1385c76..024a86f 100644
--- a/src/main/java/org/gcube/accounting/datamodel/RawUsageRecord.java
+++ b/src/main/java/org/gcube/accounting/datamodel/RawUsageRecord.java
@@ -101,6 +101,8 @@ public class RawUsageRecord implements UsageRecord, Serializable {
 		initializeValidation();
 		this.resourceSpecificProperties.put(ID, UUID.randomUUID().toString());
 		this.resourceSpecificProperties.put(RESOURCE_TYPE, this.getClass().getSimpleName());
+		Calendar calendar = Calendar.getInstance();
+		this.resourceSpecificProperties.put(CREATION_TIME, calendar.getTimeInMillis());
 	}
 	
 	public RawUsageRecord(Map<String, Serializable> properties) throws InvalidValueException {
diff --git a/src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageRecord.java b/src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageUsageRecord.java
similarity index 87%
rename from src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageRecord.java
rename to src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageUsageRecord.java
index ff6b49d..0007a6d 100644
--- a/src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageRecord.java
+++ b/src/main/java/org/gcube/accounting/datamodel/implementations/StorageUsageUsageRecord.java
@@ -3,6 +3,7 @@
  */
 package org.gcube.accounting.datamodel.implementations;
 
+import org.gcube.accounting.datamodel.validators.NotEmptyIfNotNull;
 import org.gcube.accounting.datamodel.validators.ValidIP;
 import org.gcube.accounting.exception.InvalidValueException;
 import org.gcube.common.validator.annotations.NotEmpty;
@@ -11,14 +12,14 @@ import org.gcube.common.validator.annotations.NotEmpty;
  * @author Luca Frosini (ISTI - CNR) http://www.lucafrosini.com/
  *
  */
-public class StorageUsageRecord extends StorageStatusUsageRecord {
+public class StorageUsageUsageRecord extends StorageStatusUsageRecord {
 
 	/**
 	 * Generated Serial Version UID
 	 */
 	private static final long serialVersionUID = 1381025822586583326L;
 
-	@NotEmpty
+	@NotEmptyIfNotNull
 	public static final String OBJECT_URI = "objectURI";
 	@NotEmpty
 	public static final String OPERATION_TYPE = "operationType";
@@ -26,7 +27,7 @@ public class StorageUsageRecord extends StorageStatusUsageRecord {
 	public static final String CALLER_IP = "callerIP";
 
 	
-	public StorageUsageRecord(){
+	public StorageUsageUsageRecord(){
 		super();
 	}