HCOLL-328 fixed : Possible issue with ChronicleSet on restart

src/main/java/net/openhft/chronicle/set/SetFromMap.java

@@ -37,8 +37,6 @@ class SetFromMap<E> extends AbstractSet<E>
     private transient Set<E> s;       // Its keySet
 
     SetFromMap(ChronicleMap<E, DummyValue> map) {
-        if (!map.isEmpty())
-            throw new IllegalArgumentException("Map is non-empty");
         m = map;
         s = map.keySet();
     }