Returns whether this collection is equivalent to the given collection.
In general, collections are equivalent if they have the same content.
However, length, order, and uniqueness must also be equivalent if this collection,
or the collection on the left for Object.equals, discriminate those
attributes.
For example, if the left operand is a List, Deque, or Array, order will be
significant.
If the left operand is a Set, uniqueness will matter, but order will not.
The optional second argument is the equality operator to use when comparing the
content of these collections, and defaults to Object.equals.
Compares two values and returns a number having the same relative value to zero.
Consistently returns the same string for the same object.