# Optional Path parameters are not supported...

        // As a side effect it will log the optional projects that could not be resolved.
        projectSelector.getOptionalProjectsBySelectors(request, session.getAllProjects(), allOptionalSelectors);
    }

    /**
     * Check whether any of the requested optional profiles were not activated or deactivated.
     * @param session the Maven session.
     * @param profileActivation the requested optional and required profiles.
     */

## First dependency "dependable" { #first-dependency-dependable }

You could create a first dependency ("dependable") like:

{* ../../docs_src/dependencies/tutorial005_an_py310.py hl[8:9] *}

It declares an optional query parameter `q` as a `str`, and then it just returns it.

This is quite simple (not very useful), but will help us focus on how the sub-dependencies work.

      <artifactId>commons-cli</artifactId>
    </dependency>

    <dependency>
      <groupId>ch.qos.logback</groupId>
      <artifactId>logback-classic</artifactId>
      <optional>true</optional>
    </dependency>
    <dependency>
      <groupId>org.jline</groupId>
      <artifactId>jansi-core</artifactId>
    </dependency>

    <dependency>
      <groupId>javax.inject</groupId>

 * limitations under the License.
 */

package com.google.common.io;

import static com.google.common.truth.Truth.assertThat;
import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.io.SourceSinkFactory.ByteSourceFactory;
import com.google.common.io.SourceSinkFactory.CharSourceFactory;
import java.io.BufferedReader;

    return flags.entries
        .map { entry ->
            entry.key.map {
                when (it) {
                    true -> Optional.of(entry.value)
                    false -> Optional.empty()
                }
            }.orElse(provider {
                throw GradleException("Expected boolean flag to be configured")
            })
        }

    * Les valeurs de ce dictionnaire sont de type `float`.

#### `Optional`

Vous pouvez aussi utiliser `Optional` pour déclarer qu'une variable a un type, comme `str` mais qu'il est "optionnel" signifiant qu'il pourrait aussi être `None`.

{*../../docs_src/python_types/tutorial009.py hl[1,4] *}

# OkHttp test platform rules uses optional classes.

/// note

**FastAPI** saura que la valeur de `q` n'est pas requise grâce à la valeur par défaut `=None`.

Le type `Optional` dans `Optional[str]` n'est pas utilisé par **FastAPI**, mais sera utile à votre éditeur pour améliorer le support offert par ce dernier et détecter plus facilement des erreurs de type.

///

## Sans Pydantic

For example, this model above declares a JSON "`object`" (or Python `dict`) like:

```JSON
{
    "name": "Foo",
    "description": "An optional description",
    "price": 45.2,
    "tax": 3.5
}
```

...as `description` and `tax` are optional (with a default value of `None`), this JSON "`object`" would also be valid:

```JSON