String result = checkNotNull(NON_NULL_STRING);
    assertThat(result).isSameInstanceAs(NON_NULL_STRING);
  }

  public void testCheckNotNull_simple_failure() {
    assertThrows(NullPointerException.class, () -> checkNotNull(null));
  }

  public void testCheckNotNull_simpleMessage_success() {
    String result = checkNotNull(NON_NULL_STRING, IGNORE_ME);

    this.value = value;
  }

  @Override
  @SuppressWarnings("CatchingUnchecked") // sneaky checked exception
  public void addListener(Runnable listener, Executor executor) {
    checkNotNull(listener, "Runnable was null.");
    checkNotNull(executor, "Executor was null.");
    try {
      executor.execute(listener);
    } catch (Exception e) { // sneaky checked exception

      backingMap.put(rowKey, map);
    }
    return map;
  }

  @CanIgnoreReturnValue
  @Override
  public @Nullable V put(R rowKey, C columnKey, V value) {
    checkNotNull(rowKey);
    checkNotNull(columnKey);
    checkNotNull(value);
    return getOrCreate(rowKey).put(columnKey, value);
  }

  @CanIgnoreReturnValue
  @Override

@NullUnmarked
class RandomAmountInputStream extends FilterInputStream {
  private final Random random;

  public RandomAmountInputStream(InputStream in, Random random) {
    super(checkNotNull(in));
    this.random = checkNotNull(random);
  }

  @Override
  public int read(byte[] b, int off, int len) throws IOException {
    return super.read(b, off, random.nextInt(len) + 1);
  }

      contents.add(checkNotNull(element));
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> addAll(Iterable<? extends E> elements) {
      super.addAll(elements);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<E> add(E... elements) {
      checkNotNull(elements); // for GWT
      super.add(elements);

    return fromIntBits(this.value + checkNotNull(val).value);
  }

  /**
   * Returns the result of subtracting this and {@code val}. If the result would be negative,
   * returns the low 32 bits of the result.
   *
   * @since 14.0
   */
  public UnsignedInteger minus(UnsignedInteger val) {
    return fromIntBits(value - checkNotNull(val).value);
  }

  /**

   * Enums.getIfPresent(Country.class, countryInput).or(Country.DEFAULT);}
   *
   * @since 12.0
   */
  public static <T extends Enum<T>> Optional<T> getIfPresent(Class<T> enumClass, String value) {
    checkNotNull(enumClass);
    checkNotNull(value);
    return Platform.getEnumIfPresent(enumClass, value);
  }

  private static final Map<Class<? extends Enum<?>>, Map<String, WeakReference<? extends Enum<?>>>>

  public ImmutableSortedMap<K, V> subMap(K fromKey, K toKey) {
    checkNotNull(fromKey);
    checkNotNull(toKey);
    checkArgument(comparator.compare(fromKey, toKey) <= 0);
    return newView(sortedDelegate.subMap(fromKey, toKey));
  }

  ImmutableSortedMap<K, V> subMap(K fromKey, boolean fromInclusive, K toKey, boolean toInclusive) {
    checkNotNull(fromKey);
    checkNotNull(toKey);

        return join(parts.iterator());
      }

      @Override
      public <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException {
        checkNotNull(appendable, "appendable");
        checkNotNull(parts, "parts");
        while (parts.hasNext()) {
          Object part = parts.next();
          if (part != null) {
            appendable.append(Joiner.this.toString(part));

    private final Function<B, C> g;
    private final Function<A, ? extends B> f;

    FunctionComposition(Function<B, C> g, Function<A, ? extends B> f) {
      this.g = checkNotNull(g);
      this.f = checkNotNull(f);
    }

    @Override
    @ParametricNullness
    public C apply(@ParametricNullness A a) {
      return g.apply(f.apply(a));
    }

    @Override