when(options.model()).thenReturn(Optional.empty());
        when(options.plugins()).thenReturn(Optional.empty());
        when(options.modelVersion()).thenReturn(Optional.empty());
        return options;
    }

    /**
     * Creates upgrade options with specific values.
     *
     * @param all the --all option value (null for absent)
     * @param infer the --infer option value (null for absent)

E você também pode declarar parâmetros de corpo como opcionais, definindo o valor padrão com `None`:

{* ../../docs_src/body_multiple_params/tutorial001_an_py310.py hl[18:20] *}

/// note | Nota

Repare que, neste caso, o `item` que seria capturado a partir do corpo é opcional. Visto que ele possui `None` como valor padrão.

///

    private ProtoLookup(Map<Class<?>, Object> components) {
        this.components = components;
    }

    @Override
    public <T> T lookup(Class<T> type) {
        Optional<T> optional = lookupOptional(type);
        if (optional.isPresent()) {
            return optional.get();
        } else {
            throw new LookupException("No mapping for key: " + type.getName());
        }
    }

    @Override

  @Override
  public T get() {
    return reference;
  }

  @Override
  public T or(T defaultValue) {
    checkNotNull(defaultValue, "use Optional.orNull() instead of Optional.or(null)");
    return reference;
  }

  @Override
  public Optional<T> or(Optional<? extends T> secondChoice) {
    checkNotNull(secondChoice);
    return this;
  }

  @Override
  public T or(Supplier<? extends T> supplier) {

 * under the License.
 */
package org.apache.maven.graph;

import java.io.File;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Optional;
import java.util.Set;
import java.util.stream.Collectors;

import org.apache.maven.MavenExecutionException;
import org.apache.maven.execution.MavenExecutionRequest;
import org.apache.maven.execution.ProjectActivation;

   *
   * <p><b>Java 9 users:</b> use {@code optional.stream()} instead.
   */
  @Beta
  @InlineMe(replacement = "optional.stream()")
  @InlineMeValidationDisabled("Java 9+ API only")
  public static <T> Stream<T> stream(java.util.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,

        // v1 == 0.
        .optional(defaultValue = 0),
      Adapters.INTEGER_AS_BIG_INTEGER,
      algorithmIdentifier,
      name,
      validity,
      name,
      subjectPublicKeyInfo,
      Adapters.BIT_STRING.withTag(tag = 1L).optional(),
      Adapters.BIT_STRING.withTag(tag = 2L).optional(),
      extension.asSequenceOf().withExplicitBox(tag = 3).optional(defaultValue = listOf()),
      decompose = {

            throw new LookupException(e);
        }
    }

    @Override
    public <T> Optional<T> lookupOptional(Class<T> type) {
        try {
            return Optional.of(container.lookup(type));
        } catch (ComponentLookupException e) {
            if (e.getCause() instanceof NoSuchElementException) {
                return Optional.empty();
            }
            throw new LookupException(e);
        }
    }

	trailer http.Header

	sha256 hash.Hash
}

// Options are optional arguments to NewReaderWithOpts, Options
// simply converts positional arguments to NewReader() into a
// more flexible way to provide optional inputs. This is currently
// used by the FanOut API call mostly to disable expensive md5sum
// calculation repeatedly under hash.Reader.
type Options struct {
	MD5Hex     string
	SHA256Hex  string
	Size       int64

    scope: Optional string. Several scopes (each one a string) separated by spaces. E.g.
        "items:read items:write users:read profile openid"
    client_id: optional string. OAuth2 recommends sending the client_id and client_secret (if any)
        using HTTP Basic auth, as: client_id:client_secret
    client_secret: optional string. OAuth2 recommends sending the client_id and client_secret (if any)