import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.common.base.Functions;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import com.google.common.testing.ClassSanityTester.FactoryMethodReturnsNullException;
import com.google.common.testing.ClassSanityTester.ParameterHasNoDistinctValueException;

Например, модель выше описывает такой JSON "объект" (или Python `dict`):

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

...так как `description` и `tax` являются необязательными (со значением по умолчанию `None`), такой JSON "объект" тоже будет корректным:

```JSON
{

Это не является ограничением **FastAPI**, это часть протокола HTTP.

///

## Необязательная загрузка файлов { #optional-file-upload }

Вы можете сделать загрузку файла необязательной, используя стандартные аннотации типов и установив значение по умолчанию `None`:

{* ../../docs_src/request_files/tutorial001_02_an_py310.py hl[9,17] *}

 * existing key-value pair has no effect.
 *
 * <p>Null keys and values are permitted (provided, of course, that the respective comparators
 * support them). All optional multimap methods are supported, and all returned views are
 * modifiable.
 *
 * <p>This class is not threadsafe when any concurrent operations update the multimap. Concurrent

Y tu *path operation* tiene un pequeño candado en la esquina superior derecha que puedes pulsar.

///

Y si lo haces, tendrás un pequeño formulario de autorización para escribir un `username` y `password` (y otros campos opcionales):

<img src="/img/tutorial/security/image02.png">

/// note | Nota

No importa lo que escribas en el formulario, aún no funcionará. Pero llegaremos allí.

///

                    Artifact artifact = node.getArtifact();

                    try {
                        if (node.filterTrail(filter)) {
                            // If it was optional and not a direct dependency,
                            // we don't add it or its children, just allow the update of the version and artifactScope
                            if (node.isChildOfRootNode() || !artifact.isOptional()) {

import org.dbflute.cbean.ConditionBean;
import org.dbflute.cbean.result.ListResultBean;
import org.dbflute.cbean.result.PagingResultBean;
import org.dbflute.exception.IllegalBehaviorStateException;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.util.DfTypeUtil;
import org.opensearch.action.bulk.BulkRequestBuilder;
import org.opensearch.action.delete.DeleteRequestBuilder;
import org.opensearch.action.index.IndexRequestBuilder;

import org.dbflute.cbean.ConditionBean;
import org.dbflute.cbean.result.ListResultBean;
import org.dbflute.cbean.result.PagingResultBean;
import org.dbflute.exception.IllegalBehaviorStateException;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.util.DfTypeUtil;
import org.opensearch.action.bulk.BulkRequestBuilder;
import org.opensearch.action.delete.DeleteRequestBuilder;
import org.opensearch.action.index.IndexRequestBuilder;

import org.jspecify.annotations.Nullable;

/**
 * CompactLinkedHashMap is an implementation of a Map with insertion or LRU iteration order,
 * maintained with a doubly linked list through the entries. All optional operations (put and
 * remove) are supported. Null keys and values are supported.
 *
 * <p>{@code containsKey(k)}, {@code put(k, v)} and {@code remove(k)} are all (expected and

# Apache Maven Wrapper startup batch script, version 3.3.2
#
# Required ENV vars:
# ------------------
#   JAVA_HOME - location of a JDK home dir
#
# Optional ENV vars
# -----------------
#   MAVEN_OPTS - parameters passed to the Java VM when running Maven
#     e.g. to debug Maven itself, use
#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000