diff --git a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
index 3743dab..713c1ce 100644
--- a/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
+++ b/src/main/java/org/gcube/portlets/user/td/gwtservice/server/TDGWTServiceImpl.java
@@ -6495,7 +6495,7 @@ public class TDGWTServiceImpl extends RemoteServiceServlet implements
 					
 					InvocationS invocationS=null;
 					if (job.getInvocation() != null) {
-						Map<String,Object> mapSent=new HashMap<String,Object>();
+						HashMap<String,Object> mapSent=new HashMap<String,Object>();
 						Map<String,Object> map=job.getInvocation().getParameters();
 						Set<String> keys=map.keySet();
 						Iterator<String> iterator=keys.iterator();
diff --git a/src/main/java/org/gcube/portlets/user/td/gwtservice/shared/task/InvocationS.java b/src/main/java/org/gcube/portlets/user/td/gwtservice/shared/task/InvocationS.java
index f5ba387..442f90e 100644
--- a/src/main/java/org/gcube/portlets/user/td/gwtservice/shared/task/InvocationS.java
+++ b/src/main/java/org/gcube/portlets/user/td/gwtservice/shared/task/InvocationS.java
@@ -1,6 +1,7 @@
 package org.gcube.portlets.user.td.gwtservice.shared.task;
 
 import java.io.Serializable;
+import java.util.HashMap;
 import java.util.Map;
 
 import org.gcube.portlets.user.td.gwtservice.shared.tr.RefColumn;
@@ -17,7 +18,7 @@ public class InvocationS implements Serializable {
 	protected String columnId;
 	protected long operationId;
 	protected Long identifier;
-	protected Map<String, Object> parameters;
+	protected HashMap<String, Object> parameters;
 	protected String taskId;
 	protected RefColumn refColumn;
 	
@@ -27,7 +28,7 @@ public class InvocationS implements Serializable {
 	}
 
 	public InvocationS(String columnId, long operationId, Long identifier,
-			Map<String, Object> parameters, String taskId, RefColumn refColumn) {
+			HashMap<String, Object> parameters, String taskId, RefColumn refColumn) {
 		this.columnId = columnId;
 		this.operationId = operationId;
 		this.identifier = identifier;
@@ -60,11 +61,11 @@ public class InvocationS implements Serializable {
 		this.identifier = identifier;
 	}
 
-	public Map<String, Object> getParameters() {
+	public HashMap<String, Object> getParameters() {
 		return parameters;
 	}
 
-	public void setParameters(Map<String, Object> parameters) {
+	public void setParameters(HashMap<String, Object> parameters) {
 		this.parameters = parameters;
 	}