prevKey = key;
          }
        }
        return new ImmutableSortedMap<>(
            new RegularImmutableSortedSet<K>(ImmutableList.<K>asImmutableList(keys), comparator),
            ImmutableList.<V>asImmutableList(values));
    }
  }

  /**
   * Returns a builder that creates immutable sorted maps whose keys are ordered by their natural

      // large array relative to the number of elements, so we cap the ratio.
      contents = Arrays.copyOf(contents, uniques);
    }
    return new RegularImmutableSortedSet<E>(
        ImmutableList.<E>asImmutableList(contents, uniques), comparator);
  }

  /**
   * Returns a builder that creates immutable sorted sets with an explicit comparator. If the