private <T extends Iterator<E>> void internalExecuteAndCompare(
      T reference, T target, IteratorOperation method) {
    Object referenceReturnValue = null;
    PermittedMetaException referenceException = null;
    Object targetReturnValue = null;
    Exception targetException = null;

    try {
      targetReturnValue = method.execute(target);
    } catch (Exception e) { // sneaky checked exception
      targetException = e;

      assertEquals((Character) 'b', table.get("bar", 1));
      assertNull(table.get("foo", 3));
      assertNull(table.remove(null, 1));
      assertNull(table.remove("foo", null));
      assertNull(table.remove(null, null));
      assertSize(2);
    } else {
      try {
        table.remove("foo", 3);
        fail();
      } catch (UnsupportedOperationException expected) {

  }

  @ListFeature.Require(SUPPORTS_ADD_WITH_INDEX)
  @CollectionFeature.Require(ALLOWS_NULL_VALUES)
  public void testAddAllAtIndex_nullSupported() {
    List<E> containsNull = singletonList(null);
    assertTrue("addAll(n, containsNull) should return true", getList().addAll(0, containsNull));
    /*
     * We need (E) to force interpretation of null as the single element of a
     * varargs array, not the array itself
     */

      checkMessage(expected);
    }
  }

  private static final String NON_NULL_STRING = "foo";

  public void testVerifyNotNull_simple_success() {
    String result = verifyNotNull(NON_NULL_STRING);
    assertSame(NON_NULL_STRING, result);
  }

  public void testVerifyNotNull_simple_failure() {
    try {
      verifyNotNull(null);
      fail();
    } catch (VerifyException expected) {
    }
  }

    graph.putEdgeValue(4, 4, "valueD");

    assertThat(graph.edgeValueOrDefault(1, 2, null)).isEqualTo("valueA");
    assertThat(graph.edgeValueOrDefault(2, 1, null)).isEqualTo("valueB");
    assertThat(graph.edgeValueOrDefault(2, 3, null)).isEqualTo("valueC");
    assertThat(graph.edgeValueOrDefault(4, 4, null)).isEqualTo("valueD");
    assertThat(graph.edgeValueOrDefault(1, 2, DEFAULT)).isEqualTo("valueA");

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testRetainAll_containsNonNullWithNull() {
    initCollectionWithNullElement();
    expectReturnsTrue(disjoint);
    expectContents();
  }

  // retainAll(null)

  /*
   * AbstractCollection fails the retainAll(null) test when the subject

   * the call to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *
   * @param message message to use upon assertion failure
   */
  protected void expectNullKeyMissingWhenNullKeysUnsupported(String message) {
    try {
      assertFalse(message, getMap().containsKey(null));
    } catch (NullPointerException tolerated) {

  @CollectionFeature.Require({SUPPORTS_REMOVE, ALLOWS_NULL_VALUES})
  public void testRemove_nullPresent() {
    initCollectionWithNullElement();
    assertEquals(1, getMultiset().remove(null, 2));
    assertFalse(
        "multiset contains present after multiset.remove(present, 2)",
        getMultiset().contains(null));
    assertEquals(0, getMultiset().count(null));
  }

   * ParametricNullness parametric nullness}. Sometimes, code may receive a null {@code T} but store
   * a "null sentinel" to take its place. When the time comes to convert it back to a {@code T} to
   * return to a caller, the code needs to a way to return {@code null} from a method that returns
   * "plain {@code T}." This API provides that.
   */
  @SuppressWarnings({"nullness", "TypeParameterUnusedInFormals", "ReturnMissingNullable"})

        @javax.annotation.CheckForNull String s) {
      // null?  no problem
    }

    public static void staticOneArgJsr305NullableCorrectlyDoesNotThrowNPE(
        @javax.annotation.Nullable String s) {
      // null?  no problem
    }

    public static void staticOneArgNullableCorrectlyDoesNotThrowNPE(@Nullable String s) {
      // null?  no problem
    }