// nulls are usually out of bounds for a subset, so ban them altogether
      for (Object o : elements) {
        if (o == null) {
          throw new NullPointerException();
        }
      }

      // prepare extreme values to be filtered out of view
      E firstExclusive = delegate.belowSamplesGreater();
      E lastExclusive = delegate.aboveSamplesLesser();
      if (from != Bound.NO_BOUND) {

      // nulls are usually out of bounds for a subset, so ban them altogether
      for (Object o : elements) {
        if (o == null) {
          throw new NullPointerException();
        }
      }

      // prepare extreme values to be filtered out of view
      E firstExclusive = delegate.belowSamplesGreater();
      E lastExclusive = delegate.aboveSamplesLesser();
      if (from != Bound.NO_BOUND) {

                @SuppressWarnings("unchecked")
                // map generators must past entry objects
                List<E> normalValues = (List<E>) Arrays.asList(entries);

                // prepare extreme values to be filtered out of view
                Collections.sort(extremeValues, comparator);
                E firstExclusive = extremeValues.get(1);
                E lastExclusive = extremeValues.get(2);

                @SuppressWarnings("unchecked")
                // map generators must past entry objects
                List<E> normalValues = (List<E>) Arrays.asList(entries);

                // prepare extreme values to be filtered out of view
                Collections.sort(extremeValues, comparator);
                E firstExclusive = extremeValues.get(1);
                E lastExclusive = extremeValues.get(2);

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);
    assertNull(unmodifiable.asMap().get("missing"));

    assertFalse(unmodifiable.entries() instanceof Serializable);
  }

  /** Prepares the multimap for unmodifiable tests, returning an unmodifiable view of the map. */
  private static Multimap<@Nullable String, @Nullable Integer> prepareUnmodifiableTests(
      Multimap<@Nullable String, @Nullable Integer> multimap,

    assertThat(unmodifiable.asMap().get("bar")).containsExactly(5, -1);
    assertNull(unmodifiable.asMap().get("missing"));

    assertFalse(unmodifiable.entries() instanceof Serializable);
  }

  /** Prepares the multimap for unmodifiable tests, returning an unmodifiable view of the map. */
  private static Multimap<@Nullable String, @Nullable Integer> prepareUnmodifiableTests(
      Multimap<@Nullable String, @Nullable Integer> multimap,