s that are considered equal by <code>==</code>.</p>
<p>The set allows <code>null</code> as an element.</p>
<p>Iteration of elements is done in element insertion order.
An element that was added after another will occur later in the iteration.
Adding an element that is already in the set
does not change its position in the iteration order,
but removing an element and adding it again,
will make it the last element of an iteration.</p>
<p>Most simple operations on <code>HashSet</code> are done in (potentially 