<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) {

 * Exception thrown when an error occurs during NDR encoding or decoding operations.
 */
public class NdrException extends IOException {

    /**
     * Error message for null reference pointers.
     */
    public static final String NO_NULL_REF = "ref pointer cannot be null";

    /**
     * Error message for invalid array conformance.
     */
    public static final String INVALID_CONFORMANCE = "invalid array conformance";

    /**

     * @throws SAXException if XML parsing fails
     * @throws IOException if I/O error occurs
     */
    protected String getSnapshotActualVersion(final DocumentBuilder builder, final String pluginUrl, final String version)
            throws SAXException, IOException {
        String timestamp = null;
        String buildNumber = null;

   * @return the value that was previously associated with the key, or {@code null} if there was no
   *     previous entry. (If the bimap contains null values, then {@code forcePut}, like {@code
   *     put}, returns {@code null} both if the key is absent and if it is present with a null
   *     value.)
   */
  @CanIgnoreReturnValue

        assertEquals(-1, actual);
    }

    @Test
    @DisplayName("Structure: DOS_ERROR_CODES is non-null with [code,status] pairs")
    void dosErrorCodesStructureIsValid() {
        // Arrange & Act
        int[][] table = DosError.DOS_ERROR_CODES;

        // Assert
        assertNotNull(table, "DOS_ERROR_CODES must not be null");
        assertTrue(table.length > 0, "DOS_ERROR_CODES must not be empty");

    @Override
    public ImmutableSetMultimap<K, V> build() {
      if (builderMap == null) {
        return ImmutableSetMultimap.of();
      }
      Collection<Map.Entry<K, ImmutableCollection.Builder<V>>> mapEntries = builderMap.entrySet();
      if (keyComparator != null) {
        mapEntries = Ordering.from(keyComparator).<K>onKeys().immutableSortedCopy(mapEntries);
      }

                    BadWord badWord = badWordBhv.selectEntity(cb -> cb.query().setSuggestWord_Equal(target)).orElse(null);//TODO
                    final long now = ComponentUtil.getSystemHelper().getCurrentTimeAsLong();
                    if (isDelete) {
                        badWordBhv.delete(badWord);
                    } else if (badWord == null) {
                        badWord = new BadWord();

        if (!config.isDfsDisabled()) {
            this.capabilities |= Smb2Constants.SMB2_GLOBAL_CAP_DFS;
        }

        if (config.isEncryptionEnabled() && config.getMaximumVersion() != null
                && config.getMaximumVersion().atLeast(DialectVersion.SMB300)) {
            this.capabilities |= Smb2Constants.SMB2_GLOBAL_CAP_ENCRYPTION;
        }

        final Set<DialectVersion> dvs =