getNoPurge method
Returns the value associated with key, or null if absent or collected.
Same as get, but does NOT purge entries with collected key or value.
Implementation
V? getNoPurge(Object? key) {
if (key == null || key is! K) return null;
var k = _EntryKey<K, V>(key);
// ignore: collection_methods_unrelated_type
var e = _map[k];
if (e == null) return null;
var eValue = e.payload;
return eValue;
}