when(toolchainFactoryBasicType.createDefaultToolchain()).thenReturn(Optional.of(basicToolchain));
        org.apache.maven.api.Toolchain rareToolchain = mock(org.apache.maven.api.Toolchain.class);
        when(toolchainFactoryRareType.createDefaultToolchain()).thenReturn(Optional.of(rareToolchain));

        // execute

            }

            @Override
            public <T> Optional<T> lookupOptional(Class<T> type) {
                return Optional.empty();
            }

            @Override
            public <T> Optional<T> lookupOptional(Class<T> type, String name) {
                return Optional.empty();
            }

            @Override

#### Possibly `None` (Optional)

Ви можете оголосити, що значення може мати тип, наприклад `str`, але також може бути `None`.

У Python 3.6 і вище (включаючи Python 3.10) ви можете оголосити його, імпортувавши та використовуючи `Optional` з модуля `typing`.

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

 * to add or remove multiple occurrences of an element at once, or to set the count of an element to
 * a specific value. These modification operations are optional, but implementations which support
 * the standard collection operations {@link #add(Object)} or {@link #remove(Object)} are encouraged
 * to implement the related methods as well. Finally, two collection views are provided: {@link

     * @see org.apache.maven.api.services.ArtifactManager#getPath(Artifact)
     */
    @Nonnull
    default Optional<ProducedArtifact> getMainArtifact() {
        List<ProducedArtifact> artifacts = getArtifacts();
        return artifacts.size() == 2 ? Optional.of(artifacts.get(1)) : Optional.empty();
    }

    /**

import org.codelibs.fess.opensearch.config.exentity.DuplicateHost;
import org.codelibs.fess.util.ComponentUtil;
import org.codelibs.fess.util.RenderDataUtil;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.render.RenderData;

#### `Optional`

Вы также можете использовать `Optional`, чтобы объявить, что переменная имеет тип, например, `str`, но это является «необязательным», что означает, что она также может быть `None`:

```Python hl_lines="1  4"
{!../../docs_src/python_types/tutorial009.py!}
```

  /** Puts all the associations from {@code rangeMap} into this range map (optional operation). */
  void putAll(RangeMap<K, ? extends V> rangeMap);

  /** Removes all associations from this range map (optional operation). */
  void clear();

  /**
   * Removes all associations from this range map in the specified range (optional operation).
   *

import org.codelibs.fess.dict.DictionaryManager;
import org.codelibs.fess.dict.stopwords.StopwordsFile;
import org.codelibs.fess.dict.stopwords.StopwordsItem;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.dbflute.optional.OptionalEntity;

import jakarta.annotation.Resource;

/**
 * Service for managing stopwords.
 * This class provides methods to interact with stopwords dictionaries,

import org.codelibs.fess.dict.DictionaryManager;
import org.codelibs.fess.dict.synonym.SynonymFile;
import org.codelibs.fess.dict.synonym.SynonymItem;
import org.codelibs.fess.mylasta.direction.FessConfig;
import org.dbflute.optional.OptionalEntity;

import jakarta.annotation.Resource;

/**
 * Service for managing synonyms.
 * This class provides methods to interact with synonym dictionaries,