/guava/guava-gwt/src-super/com/google/common/collect/super/com/google/common/collect/ImmutableSortedSet.java
this.comparator = checkNotNull( null) ;
this.comparator = checkNotNull ( comparator ) ;
public static <E extends Comparable<?>> Builder<E> naturalOrder() { return new Builder<E>(Ordering.natural()); } public static final class Builder<E> extends ImmutableSet.Builder<E> { private final Comparator<? super E> comparator; public Builder(Comparator<? super E> comparator) { <extra_id_0> } @CanIgnoreReturnValue @Override public Builder<E> add(E element) { super.add(element); return this;