assertThat(ArbitraryInstances.get(Object.class)).isNotNull();
    assertEquals(0, ArbitraryInstances.get(Number.class));
    assertEquals(UTF_8, ArbitraryInstances.get(Charset.class));
    assertEquals(Optional.empty(), ArbitraryInstances.get(Optional.class));
    assertEquals(OptionalInt.empty(), ArbitraryInstances.get(OptionalInt.class));
    assertEquals(OptionalLong.empty(), ArbitraryInstances.get(OptionalLong.class));

import com.google.common.collect.testing.features.TesterAnnotation;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Set;

/**
 * Optional features of classes derived from {@code Multimap}.
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible

import com.google.common.collect.testing.features.TesterAnnotation;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Set;

/**
 * Optional features of classes derived from {@code Multimap}.
 *
 * @author Louis Wasserman
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible

import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.List;
import java.util.Set;

/**
 * Optional features of classes derived from {@code List}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible

      <version>0.2</version>
      <scope>import</scope>
    </dependency>
    <dependency>
      <groupId>test</groupId>
      <artifactId>g</artifactId>
      <version>0.2</version>
      <scope>optional</scope>
    </dependency>
  </dependencies>

     * Required field with maximum length of 100 characters.
     */
    @Required
    @Size(max = 100)
    public String name;

    /**
     * The version of the plugin to delete.
     * Optional field with maximum length of 100 characters.
     */
    @Size(max = 100)
    public String version;

import com.google.common.annotations.GwtCompatible;
import java.lang.annotation.Inherited;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.Set;

/**
 * Optional features of classes derived from {@code Set}.
 *
 * @author George van den Driessche
 */
@SuppressWarnings("rawtypes") // maybe avoidable if we rework the whole package?
@GwtCompatible

    ) : Closeable by body

    internal companion object {
      /** These options follow the boundary. */
      val afterBoundaryOptions =
        Options.of(
          // 0.  "\r\n"  More parts.
          "\r\n".encodeUtf8(),
          // 1.  "--"    No more parts.
          "--".encodeUtf8(),
          // 2.  " "     Optional whitespace. Only used if there are more parts.
          " ".encodeUtf8(),

Das ist keine Limitation von **FastAPI**, sondern Teil des HTTP-Protokolls.

///

## Optionaler Datei-Upload { #optional-file-upload }

Sie können eine Datei optional machen, indem Sie Standard-Typannotationen verwenden und den Defaultwert auf `None` setzen:

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

import org.lastaflute.web.validation.Required;

/**
 * Form for uploading files to the storage system via the admin API.
 * This form is used in the admin API interface to upload files to the storage backend
 * with optional path specification for file organization.
 */
public class UploadForm {

    /**
     * The storage path where the file should be uploaded.
     * If not specified, the file will be stored in the default location.