default boolean elementKeysAreEqual(Object other) {
            return equals(other);
        }
The interface which elements of this collection must implement.  The prev,
setPrev, next, and setNext functions handle manipulating the implicit linked
list which these elements reside in inside the collection.
elementKeysAreEqual() is the function which this collection uses to compare
elements.
clients/src/main/java/org/apache/kafka/common/utils/ImplicitLinkedHashCollection.java