Constructs a new, empty tree set, sorted according to the specified
comparator. All elements inserted into the set must be <i>mutually
comparable</i> by the specified comparator: {@code comparator.compare(e1,
e2)} must not throw a {@code ClassCastException} for any elements
{@code e1} and {@code e2} in the set. If the user attempts to add
an element to the set that violates this constraint, the
{@code add} call will throw a {@code ClassCastException}.
@param comparator the comparator that will be used to order this set.
If {@code null}, the {@linkplain Comparable natural
ordering} of the elements will be used.
Constructs a new, empty tree set, sorted according to the specified comparator. All elements inserted into the set must be <i>mutually comparable</i> by the specified comparator: {@code comparator.compare(e1, e2)} must not throw a {@code ClassCastException} for any elements {@code e1} and {@code e2} in the set. If the user attempts to add an element to the set that violates this constraint, the {@code add} call will throw a {@code ClassCastException}.
@param comparator the comparator that will be used to order this set. If {@code null}, the {@linkplain Comparable natural ordering} of the elements will be used.