@CollectionFeature.Require(absent = ALLOWS_NULL_VALUES)
  public void testSet_nullUnsupported() {
    try {
      getList().set(aValidIndex(), null);
      fail("set(null) should throw NullPointerException");
    } catch (NullPointerException expected) {
    }
    expectUnchanged();
  }

  private int aValidIndex() {
    return getList().size() / 2;
  }

  /**

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

  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testRemove_nullKeyQueriesUnsupported() {
    try {
      assertFalse(getMap().remove(null, v3()));
    } catch (NullPointerException tolerated) {
      // since the operation would be a no-op, the exception is not required
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_VALUE_QUERIES)

  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_KEY_QUERIES)
  public void testRemove_nullKeyQueriesUnsupported() {
    try {
      assertFalse(getMap().remove(null, v3()));
    } catch (NullPointerException tolerated) {
      // since the operation would be a no-op, the exception is not required
    }
    expectUnchanged();
  }

  @MapFeature.Require(value = SUPPORTS_REMOVE, absent = ALLOWS_NULL_VALUE_QUERIES)

  @MapFeature.Require(value = SUPPORTS_PUT, absent = ALLOWS_NULL_KEYS)
  public void testPut_nullKeyUnsupported() {
    try {
      put(nullKeyEntry);
      fail("put(null, value) should throw");
    } catch (NullPointerException expected) {
    }
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported put(null, value)");
  }

   * Stream.of(stream1, stream2, ...).flatMap(s -> s)}. If the sources are iterables, use {@code
   * Stream.of(iter1, iter2, ...).flatMap(Streams::stream)}.
   *
   * @throws NullPointerException if any of the provided iterables is {@code null}
   * @since 20.0
   */
  @SafeVarargs
  public static <T extends @Nullable Object> FluentIterable<T> concat(
      Iterable<? extends T>... inputs) {

  public void testSetValueNullUnsupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      try {
        entry.setValue(null);
        fail("Expected NullPointerException");
      } catch (NullPointerException expected) {
      }
      expectUnchanged();
    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

  public void testSetValueNullUnsupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      try {
        entry.setValue(null);
        fail("Expected NullPointerException");
      } catch (NullPointerException expected) {
      }
      expectUnchanged();
    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)

    assertSame(NON_NULL_STRING, result);
  }

  public void testCheckNotNull_simple_failure() {
    try {
      Preconditions.checkNotNull(null);
      fail("no exception thrown");
    } catch (NullPointerException expected) {
    }
  }

  public void testCheckNotNull_simpleMessage_success() {
    String result = Preconditions.checkNotNull(NON_NULL_STRING, IGNORE_ME);
    assertSame(NON_NULL_STRING, result);
  }

   * input element is mapped to one cell in the returned table, with the rows, columns, and values
   * generated by applying the specified functions.
   *
   * <p>The returned {@code Collector} will throw a {@code NullPointerException} at collection time
   * if the row, column, or value functions return null on any input.
   *
   * @since 33.2.0 (available since 21.0 in guava-jre)
   */