Two Collection objects are equal if either both implement the List interface and contain the same items in the same order or both implement the Set interface and contain the same items in any order....

Two Collection objects are equal if either both implement the List interface and contain the same items in the same order or both implement the Set interface and contain the same items in any order. Otherwise, the Collection objects are not equal. Provide, in AbstractCollection, an implementation of equals that follows this general contract. Additionally, provide a hashCode method in AbstractCollection that follows the general contract of hashCode. (Do this by using an iterator and adding the hashCodes of all the entries. Watch out for null entries.)