*
   * @throws NullPointerException if any element is null
   */
  public static <E extends Comparable<? super E>> ImmutableSortedMultiset<E> of(
      E e1, E e2, E e3, E e4) {
    return copyOf(Ordering.natural(), Arrays.asList(e1, e2, e3, e4));
  }

  /**
   * Returns an immutable sorted multiset containing the given elements sorted by their natural
   * ordering.
   *
   * @throws NullPointerException if any element is null

    assertThrows(NullPointerException.class, () -> builder.put(null, 1));
    assertThrows(NullPointerException.class, () -> builder.putAll(null, Arrays.asList(1, 2, 3)));
    assertThrows(NullPointerException.class, () -> builder.putAll(null, 1, 2, 3));
    assertThrows(
        NullPointerException.class, () -> builder.putAll((Multimap<String, Integer>) toPut));
  }

              });
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {
    }
  }

  public void testMergeNullFunction() {
    try {
      getMap().merge(k0(), v3(), null);
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {

              });
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {
    }
  }

  public void testMergeNullFunction() {
    try {
      getMap().merge(k0(), v3(), null);
      fail("Expected NullPointerException or UnsupportedOperationException");
    } catch (NullPointerException | UnsupportedOperationException expected) {

        if (element == null) {
          throw new NullPointerException();
        }
      }
    }
  }

  @Override
  public int size() {
    return contents.length;
  }

  @Override
  public boolean contains(@Nullable Object object) {
    if (!allowNulls) {
      // behave badly
      if (object == null) {
        throw new NullPointerException();
      }
    }

    expectAdded((E) null);
  }

  @CollectionFeature.Require(value = SUPPORTS_ADD, absent = ALLOWS_NULL_VALUES)
  public void testOffer_nullUnsupported() {
    assertThrows(NullPointerException.class, () -> getQueue().offer(null));
    expectUnchanged();
    expectNullMissingWhenNullUnsupported("Should not contain null after unsupported offer(null)");
  }

    assertSize(3);
    assertThrows(NullPointerException.class, () -> table.put(null, 2, cellValue('d')));
    assertThrows(NullPointerException.class, () -> table.put("cat", null, cellValue('d')));
    if (supportsNullValues()) {
      assertNull(table.put("cat", 2, null));
      assertTrue(table.contains("cat", 2));
    } else {
      assertThrows(NullPointerException.class, () -> table.put("cat", 2, null));
    }

    ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
    assertThrows(NullPointerException.class, () -> builder.add((String) null));
  }

  public void testBuilderAddAllHandlesNullsCorrectly() {
    {
      ImmutableMultiset.Builder<String> builder = ImmutableMultiset.builder();
      assertThrows(NullPointerException.class, () -> builder.addAll((Collection<String>) null));
    }

    {

    }

    public void test_hashCode_withNullInput() {
        // Test hashCode with null input should throw NullPointerException
        ProtwordsItem item = new ProtwordsItem(1, null);
        try {
            item.hashCode();
            fail("Expected NullPointerException");
        } catch (NullPointerException e) {
            // Expected
        }
    }

    public void test_equals() {

    Integer n = null;
    assertThrows(NullPointerException.class, () -> ImmutableSortedMap.of(n, 1));

    assertThrows(NullPointerException.class, () -> ImmutableSortedMap.of("one", 1, null, 2));
  }

  public void testOfNullValue() {
    assertThrows(NullPointerException.class, () -> ImmutableSortedMap.of("one", null));

    assertThrows(NullPointerException.class, () -> ImmutableSortedMap.of("one", 1, "two", null));