guava/src/com/google/common/collect/ImmutableSortedMultiset.java
public static <E> Collector<E, ?, ImmutableSortedMultiset<E>> toImmutableSortedMultiset(
      Comparator<? super E> comparator) {
    return toImmutableSortedMultiset(comparator, Function.identity(), e -> 1);
  }
public static <E> Collector<E, ?, ImmutableSortedMultiset<E>> toImmutableSortedMultiset(
      Comparator<? super E> comparator) {
    return toImmutableSortedMultiset(comparator, Function.identity(), e -> 1);
  }
Returns a {@code Collector} that accumulates the input elements into a new {@code
ImmutableMultiset}. Elements are sorted by the specified comparator.

<p><b>Warning:</b> {@code comparator} should be <i>consistent with {@code equals}</i> as
explained in the {@link Comparator} documentation.

@since 21.0