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

Isso significa que ele **sempre terá um valor**, só que às vezes o valor pode ser `None` (ou `null` em termos de JSON).

/**
 * XML reader and writer classes for Maven POM, generated from <code>maven.mdo</code> model.
 * These classes use
 * <a href="https://codehaus-plexus.github.io/plexus-utils/apidocs/org/codehaus/plexus/util/xml/pull/package-summary.html">plexus-utils'
 * XML Pull Parser API</a> for their internal XML handling and
 * <a href="https://codehaus-plexus.github.io/plexus-utils/apidocs/org/codehaus/plexus/util/xml/Xpp3DomBuilder.html">Xpp3DomBuilder</a> +

   *
   * <p><b>Note:</b> essentially the only reason to use this method is when you will need to add or
   * remove elements later. Otherwise, for non-null elements use {@link ImmutableList#of()} (for
   * varargs) or {@link ImmutableList#copyOf(Object[])} (for an array) instead. If any elements
   * might be null, or you need support for {@link List#set(int, Object)}, use {@link
   * Arrays#asList}.
   *

     * Gets the identifier of this repository.
     *
     * @return the (case-sensitive) identifier, never {@code null}
     */
    @Nonnull
    String getId();

    /**
     * Gets the type of the repository, for example "default".
     *
     * @return the (case-sensitive) type of the repository, never {@code null}
     */
    @Nonnull
    String getType();

        }

        @Override
        public String[] getGroupNames() {
            return groups;
        }

        @Override
        public String[] getPermissions() {
            if (permissions == null) {
                final SystemHelper systemHelper = ComponentUtil.getSystemHelper();
                final Set<String> permissionSet = new HashSet<>();
                final UserInfo userInfo = authResult.getUserInfo();

    }

    protected void setupListCondition(final AccessTokenCB cb, final AccessTokenPager accessTokenPager) {
        if (accessTokenPager.id != null) {
            cb.query().docMeta().setId_Equal(accessTokenPager.id);
        }
        // TODO Long, Integer, String supported only.

        // setup condition
        cb.query().addOrderBy_Name_Asc();

                    return groovyShell.evaluate(template);
                } catch (final JobProcessingException e) {
                    throw e;
                } catch (final Exception e) {
                    return null;
                } finally {
                    final GroovyClassLoader loader = groovyShell.getClassLoader();
                    loader.clearCache();
                }
            }

            @Override

    boolean ran = false;
    @Nullable Callback callback = null;

    public SimpleTearDown() {}

    public SimpleTearDown(Callback callback) {
      this.callback = callback;
    }

    @Override
    public void tearDown() throws Exception {
      if (callback != null) {
        callback.run();
      }
      ran = true;
    }
  }

  fun value(index: Int): String = encodedValue(index).percentDecode(plusIsSpace = true)

  override fun contentType(): MediaType = CONTENT_TYPE

  override fun contentLength(): Long = writeOrCountBytes(null, true)

  @Throws(IOException::class)
  override fun writeTo(sink: BufferedSink) {
    writeOrCountBytes(sink, false)
  }

  /**

  }

  @Override
  @CheckForNull
  public Entry<E> firstEntry() {
    return isEmpty() ? null : getEntry(0);
  }

  @Override
  @CheckForNull
  public Entry<E> lastEntry() {
    return isEmpty() ? null : getEntry(length - 1);
  }

  @Override
  public int count(@CheckForNull Object element) {
    int index = elementSet.indexOf(element);