diff --git a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceBackendQuery.java b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceBackendQuery.java
index 99c19f8..04422be 100644
--- a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceBackendQuery.java
+++ b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceBackendQuery.java
@@ -30,7 +30,7 @@ public abstract class AccountingPersistenceBackendQuery {
 	 * #Info is the value. The result is relative to an Usage Record Type,
 	 * respect a TemporalConstraint and can be applied one or more filters.
 	 * 
-	 * @param aggregatedRecordClass
+	 * @param clz
 	 *            the Record Class of interest
 	 * @param temporalConstraint
 	 *            the TemporalConstraint (interval and aggregation)
@@ -47,7 +47,7 @@ public abstract class AccountingPersistenceBackendQuery {
 	 *             if fails
 	 */
 	public abstract SortedMap<Calendar, Info> getTimeSeries(
-			Class<? extends AggregatedRecord<?, ?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters)
 			throws Exception;
 
@@ -58,7 +58,7 @@ public abstract class AccountingPersistenceBackendQuery {
 	 * an Exception is thrown. The values are ordered from the most occurred
 	 * value.
 	 * 
-	 * @param aggregatedRecordClass
+	 * @param clz
 	 *            the Usage Record Class of interest
 	 * @param temporalConstraint
 	 *            the TemporalConstraint (interval and aggregation)
@@ -77,17 +77,17 @@ public abstract class AccountingPersistenceBackendQuery {
 	 *             if fails
 	 */
 	public SortedMap<NumberedFilter, SortedMap<Calendar, Info>> getTopValues(
-			Class<? extends AggregatedRecord<?, ?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters)
 			throws Exception {
 		String orderingProperty = AccountingPersistenceQuery
-				.getDefaultOrderingProperties(aggregatedRecordClass);
-		return getTopValues(aggregatedRecordClass, temporalConstraint, filters,
+				.getDefaultOrderingProperties(clz);
+		return getTopValues(clz, temporalConstraint, filters,
 				orderingProperty);
 	}
 
 	public abstract SortedMap<NumberedFilter, SortedMap<Calendar, Info>> getTopValues(
-			Class<? extends AggregatedRecord<?, ?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters,
 			String orderingProperty) throws Exception;
 
@@ -98,7 +98,7 @@ public abstract class AccountingPersistenceBackendQuery {
 	 * allowed otherwise an Exception is thrown. The values are ordered from the
 	 * most occurred value.
 	 * 
-	 * @param aggregatedRecordClass
+	 * @param clz
 	 *            the Usage Record Class of interest
 	 * @param temporalConstraint
 	 *            the TemporalConstraint (interval and aggregation)
@@ -117,17 +117,17 @@ public abstract class AccountingPersistenceBackendQuery {
 	 *             if fails
 	 */
 	public SortedSet<NumberedFilter> getNextPossibleValues(
-			Class<? extends AggregatedRecord<?, ?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters)
 			throws Exception {
 		String orderingProperty = AccountingPersistenceQuery
-				.getDefaultOrderingProperties(aggregatedRecordClass);
-		return getNextPossibleValues(aggregatedRecordClass, temporalConstraint,
+				.getDefaultOrderingProperties(clz);
+		return getNextPossibleValues(clz, temporalConstraint,
 				filters, orderingProperty);
 	}
 
 	public abstract SortedSet<NumberedFilter> getNextPossibleValues(
-			Class<? extends AggregatedRecord<?, ?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?, ?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters,
 			String orderingProperty) throws Exception;
 
diff --git a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
index a392874..ce388a8 100644
--- a/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
+++ b/src/main/java/org/gcube/accounting/analytics/persistence/AccountingPersistenceQuery.java
@@ -61,14 +61,14 @@ public class AccountingPersistenceQuery {
 	}
 
 	public static SortedSet<String> getQuerableKeys(
-			Class<? extends AggregatedRecord<?,?>> aggregatedRecordClass)
+			Class<? extends AggregatedRecord<?,?>> clz)
 			throws Exception {
-		AggregatedRecord<?,?> instance = aggregatedRecordClass.newInstance();
+		AggregatedRecord<?,?> instance = clz.newInstance();
 		return getQuerableKeys(instance);
 	}
 	
-	public static String getDefaultOrderingProperties(Class<? extends AggregatedRecord<?, ?>> recordClass){
-		if(recordClass.isAssignableFrom(AggregatedStorageUsageRecord.class)){
+	public static String getDefaultOrderingProperties(Class<? extends AggregatedRecord<?, ?>> clz){
+		if(clz.isAssignableFrom(AggregatedStorageUsageRecord.class)){
 			return AggregatedStorageUsageRecord.DATA_VOLUME;
 		}
 		return AggregatedRecord.OPERATION_COUNT;
@@ -119,12 +119,12 @@ public class AccountingPersistenceQuery {
 	}
 
 	public SortedMap<Calendar, Info> getTimeSeries(
-			Class<? extends AggregatedRecord<?,?>> aggregatedRecordClass,
-			TemporalConstraint temporalConstraint, List<Filter> filters, boolean pad)
-			throws Exception {
+			Class<? extends AggregatedRecord<?,?>> clz,
+			TemporalConstraint temporalConstraint, List<Filter> filters, 
+			boolean pad) throws Exception {
 		SortedMap<Calendar, Info> ret = 
 				AccountingPersistenceBackendQueryFactory.getInstance()
-				.getTimeSeries(aggregatedRecordClass, temporalConstraint, 
+				.getTimeSeries(clz, temporalConstraint, 
 						filters);
 		
 		if(pad){
@@ -135,18 +135,18 @@ public class AccountingPersistenceQuery {
 	}
 
 	public SortedMap<NumberedFilter, SortedMap<Calendar, Info>> getTopValues(
-			Class<? extends AggregatedRecord<?,?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters, 
 			String orderingProperty, boolean pad, int limit) throws Exception {
 		
 		SortedMap<NumberedFilter, SortedMap<Calendar, Info>> ret;
 		
 		if(orderingProperty==null){
-			orderingProperty = getDefaultOrderingProperties(aggregatedRecordClass);
+			orderingProperty = getDefaultOrderingProperties(clz);
 		}
 		
 		ret = AccountingPersistenceBackendQueryFactory.getInstance()
-				.getTopValues(aggregatedRecordClass, temporalConstraint,
+				.getTopValues(clz, temporalConstraint,
 				filters, orderingProperty);
 		
 		
@@ -163,20 +163,20 @@ public class AccountingPersistenceQuery {
 	}
 	
 	public SortedMap<NumberedFilter, SortedMap<Calendar, Info>> getTopValues(
-			Class<? extends AggregatedRecord<?,?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters)
 			throws Exception {
 		return AccountingPersistenceBackendQueryFactory.getInstance()
-				.getTopValues(aggregatedRecordClass, temporalConstraint,
+				.getTopValues(clz, temporalConstraint,
 						filters);
 	}
 
 	public SortedSet<NumberedFilter> getNextPossibleValues(
-			Class<? extends AggregatedRecord<?,?>> aggregatedRecordClass,
+			Class<? extends AggregatedRecord<?,?>> clz,
 			TemporalConstraint temporalConstraint, List<Filter> filters)
 			throws Exception {
 		return AccountingPersistenceBackendQueryFactory.getInstance()
-				.getNextPossibleValues(aggregatedRecordClass,
+				.getNextPossibleValues(clz,
 						temporalConstraint, filters);
 	}