public HashSet<EnvironmentObject> getObjectsAt(XYLocation loc)
{
HashSet<EnvironmentObject> objectsAt = objsAtLocation.get(loc);
if (null == objectsAt)
{
// Always ensure an empty Set is returned
objectsAt = new LinkedHashSet<EnvironmentObject>();
objsAtLocation.put(loc, objectsAt);
}
return objectsAt;
}