Fixed toString

src/main/java/org/gcube/informationsystem/queries/templates/impl/properties/TemplateVariableImpl.java

@@ -33,6 +33,9 @@ public class TemplateVariableImpl extends PropertyElementImpl implements Templat
 	
 	public TemplateVariableImpl() {
 		super();
+		/* TODO consider if we want to have a default type
+		 * setPropertyType(PropertyTypeName.BaseType.STRING.name());
+		 */
 	}
 
 	@Override
@@ -119,7 +122,7 @@ public class TemplateVariableImpl extends PropertyElementImpl implements Templat
 				+ ", max=" + max 
 				+ ", min=" + min
 				+ ", regexpr=" + regexp 
-				+ ", type=" + propertyTypeName.toString() 
+				+ ", type=" + (propertyTypeName==null ?  "null" : propertyTypeName.toString())
 				+ ", defaultValue=" + (defaultValue == null ? "null" : defaultValue.toString())
 				+ "]";
 	}