HE-Collection
HE-Collections - independent from hashCode() and equals(Object)
...Otherwise, the behavoir of the Java-Standard-Collection is not determined.
HE-Collections where implemente in order to store objects in a collection, that brake the contract between equals(Object) and hashCode(), HE-Collections behave predictably even if they contain objects that don't obey the contract. The name "HE" stands for Hashcode and Equals.