The string will be checked to be a valid URL, and documented in JSON Schema / OpenAPI as such.

## Attributes with lists of submodels { #attributes-with-lists-of-submodels }

You can also use Pydantic models as subtypes of `list`, `set`, etc.:

{* ../../docs_src/body_nested_models/tutorial006_py310.py hl[18] *}

This will expect (convert, validate, document, etc.) a JSON body like:

```JSON hl_lines="11"
{

     * have the same nullness as E." Since we can't, we declare it to return nullable elements, and
     * we can override it in our non-null-guaranteeing subtypes to present a better signature to
     * their users.
     *
     * However, the checker *we* use has this special knowledge about `Collection.toArray()` anyway,

 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableMultimap} as a type (as with
 * {@link Multimap} itself). Prefer subtypes such as {@link ImmutableSetMultimap} or {@link
 * ImmutableListMultimap}, which have well-defined {@link #equals} semantics, thus avoiding a common
 * source of bugs and confusion.
 *

 * Tests our AtomicHelper fallback strategy in AggregateFutureState.
 *
 * <p>On different platforms AggregateFutureState uses different strategies for its core
 * synchronization primitives. The strategies are all implemented as subtypes of AtomicHelper and
 * the strategy is selected in the static initializer of AggregateFutureState. This is convenient
 * and performant but introduces some testing difficulties. This test exercises the two fallback
 * strategies.

/**
 * Tests our AtomicHelper fallback strategies in AbstractFuture.
 *
 * <p>On different platforms AbstractFuture uses different strategies for its core synchronization
 * primitives. The strategies are all implemented as subtypes of AtomicHelper and the strategy is
 * selected in the static initializer of AbstractFuture. This is convenient and performant but
 * introduces some testing difficulties. This test exercises the fallback strategies.
 *

 * detailed at {@link ImmutableCollection}.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableMultimap} as a type (as with
 * {@link Multimap} itself). Prefer subtypes such as {@link ImmutableSetMultimap} or {@link
 * ImmutableListMultimap}, which have well-defined {@link #equals} semantics, thus avoiding a common
 * source of bugs and confusion.
 *

      }
    }

  companion object {
    /**
     * The "mixed" subtype of "multipart" is intended for use when the body parts are independent
     * and need to be bundled in a particular order. Any "multipart" subtypes that an implementation
     * does not recognize must be treated as being of subtype "mixed".
     */
    @JvmField
    val MIXED = "multipart/mixed".toMediaType()

    /**

   * restrictive. However, the ideal signature, {@code public <S super T> S or(S)}, is not legal
   * Java. As a result, some sensible operations involving subtypes are compile errors:
   *
   * {@snippet :
   * Optional<Integer> optionalInt = getSomeOptionalInt();
   * Number value = optionalInt.or(0.5); // error
   *

 * guarantees detailed below.
 *
 * <p><b>Warning:</b> avoid <i>direct</i> usage of {@link ImmutableCollection} as a type (just as
 * with {@link Collection} itself). Prefer subtypes such as {@link ImmutableSet} or {@link
 * ImmutableList}, which have well-defined {@link #equals} semantics, thus avoiding a common source
 * of bugs and confusion.
 *
 * <h3>About <i>all</i> {@code Immutable-} collections</h3>

  <mime-type type="application/msword2">
    <!-- Pre-OLE2, not a subtype of application/x-tika-msoffice -->
    <_comment>Microsoft Word 2 Document</_comment>
    <magic priority="50">
      <match value="0x9ba5" type="string" />
      <match value="0xdba5" type="string" />
    </magic>
  </mime-type>
  <mime-type type="application/msword5">
    <!-- Pre-OLE2, not a subtype of application/x-tika-msoffice -->