Bug 81070 ElementMapper should not use Integer keys computed from System#identityHashCode
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/WorkingSetModel.java
} else if (current instanceof List) {
				List list= (List)current;
				list.remove(value);
				switch (list.size()) {
					case 0:
						map.remove(key);
						break;
					case 1:
						map.put(key, list.get(0));
						break;
				}
			} else if (current == value) {
				map.remove(key);
			}
		}
		private Object getFirstElement(Map map, Object key) {
			Object obj= map.get(key);
			if (obj instanceof List) 
				return ((List)obj).get(0);
			return obj;
		}
		private List getAllElements(Map map, Object key) {
			Object obj= map.get(key);
			if (obj instanceof List)
				return (List)obj;
			if (obj == null)
				return new ArrayList(0);
			List result= new ArrayList(1);
			result.add(obj);
			return result;