1 <p>The entrySet() method is allowed to return a view of the underlying Map in which a single Entry
2 object is reused and returned during the iteration. As of Java 1.6, both IdentityHashMap and EnumMap
3 did so. When iterating through such a Map, the Entry value is only valid until you advance to the
4 next iteration. If, for example, you try to pass such an entrySet to an addAll method, things will