Handle the case where the item list is allowed to be null.
diff --git a/org.eclipse.rmf.reqif10.search/src/org/eclipse/rmf/reqif10/search/filter/EnumFilter.java b/org.eclipse.rmf.reqif10.search/src/org/eclipse/rmf/reqif10/search/filter/EnumFilter.java
index 637c39d..4487a4d 100644
--- a/org.eclipse.rmf.reqif10.search/src/org/eclipse/rmf/reqif10/search/filter/EnumFilter.java
+++ b/org.eclipse.rmf.reqif10.search/src/org/eclipse/rmf/reqif10/search/filter/EnumFilter.java
@@ -56,7 +56,7 @@
 		
 		this.attributeDefinition = attributeDefinition;
 		this.operator = operator;
-		this.filterValues =  new HashSet<EnumValue>(value);
+		this.filterValues = value == null ? new HashSet<EnumValue>() : new HashSet<EnumValue>(value);
 		if (attributeDefinition.getDefaultValue() != null){
 			this.defaultValues = new HashSet<EnumValue>(attributeDefinition.getDefaultValue().getValues());
 		}else{