validate(form, messages -> {}, validationErrorLambda);

        if (!form.newPassword.equals(form.confirmNewPassword)) {
            form.newPassword = null;
            form.confirmNewPassword = null;
            throwValidationError(messages -> {
                messages.addErrorsInvalidConfirmPassword(GLOBAL);
            }, validationErrorLambda);
        }

      assertThrows(NullPointerException.class, () -> entry.setValue(null));
      expectUnchanged();
    }
  }

  @MapFeature.Require({SUPPORTS_PUT, ALLOWS_NULL_VALUES})
  @CollectionSize.Require(absent = ZERO)
  public void testSetValueNullSupported() {
    for (Entry<K, V> entry : getMap().entrySet()) {
      if (entry.getKey().equals(k0())) {
        entry.setValue(null);
      }
    }
    expectReplacement(entry(k0(), (V) null));

                continue;
            }
        }
        return null;
    }

    protected abstract SmbResource adapt(FileEntry e) throws MalformedURLException;

    /**
     * {@inheritDoc}
     *
     * @see java.util.Iterator#hasNext()
     */
    @Override
    public boolean hasNext() {
        return this.next != null;
    }

    /**
     * {@inheritDoc}
     *

                    MultiChannelManager.class.getDeclaredMethod("createChannelTransport", InetAddress.class, InetAddress.class);
            method.setAccessible(true);
            method.invoke(multiChannelManager, null, null);
        });

        // Check that the root cause is CIFSException
        assertTrue(exception instanceof java.lang.reflect.InvocationTargetException);

    Class<?> rawType = type.getRawType();
    List<Object> samples = sampleInstances.get(rawType);
    Object sample = pickInstance(samples, null);
    if (sample != null) {
      return sample;
    }
    if (rawType.isEnum()) {
      return pickInstance(rawType.getEnumConstants(), null);
    }
    if (type.isArray()) {
      TypeToken<?> componentType = requireNonNull(type.getComponentType());

    } else if (code in 1004..1006 || code in 1015..2999) {
      "Code $code is reserved and may not be used."
    } else {
      null
    }

  fun validateCloseCode(code: Int) {
    val message = closeCodeExceptionMessage(code)
    require(message == null) { message!! }
  }

  fun acceptHeader(key: String): String = (key + ACCEPT_MAGIC).encodeUtf8().sha1().base64()

          public @Nullable Void call() throws Exception {
            // adds two nanoseconds to the ticker
            ticker.advance(1L);
            Thread.sleep(10);
            ticker.advance(1L);
            return null;
          }
        });

    assertEquals(numberOfThreads * 2, ticker.read());
  }

  @GwtIncompatible // concurrency

  public void testConcurrentAutoIncrementStep() throws Exception {

<div class="screenshot">
<img src="/img/tutorial/separate-openapi-schemas/image02.png">
</div>

Esto significa que **siempre tendrá un valor**, solo que a veces el valor podría ser `None` (o `null` en JSON).

            @Throws(IOException::class)
            override fun authenticate(route: Route?, response: Response): Request? {
              if (response.request.header("Authorization") != null) {
                return null // Give up, we've already attempted to authenticate.
              }

              println("Authenticating for response: $response")
              println("Challenges: ${response.challenges()}")

    /**
     * Do not instantiate.
     */
    protected OutputStreamUtil() {
    }

    /**
     * Creates a {@link FileOutputStream}.
     *
     * @param file the file (must not be {@literal null})
     * @return a {@link FileOutputStream} to output to the file
     * @see FileOutputStream#FileOutputStream(File)
     */
    public static FileOutputStream create(final File file) {