* it.
     */
    setResult(transformResult);
  }

  /** Template method for subtypes to actually run the transform. */
  @ForOverride
  @ParametricNullness
  abstract T doTransform(F function, @ParametricNullness I result) throws Exception;

  /** Template method for subtypes to actually set the result. */
  @ForOverride
  abstract void setResult(@ParametricNullness T result);

  @Override

      return resultString + superString;
    }
    return null;
  }

  /** Template method for subtypes to actually run the fallback. */
  @ForOverride
  @ParametricNullness
  abstract T doFallback(F fallback, X throwable) throws Exception;

  /** Template method for subtypes to actually set the result. */
  @ForOverride
  abstract void setResult(@ParametricNullness T result);

  @Override

```

////

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

## Attributes with lists of submodels

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

//// tab | Python 3.10+

```Python hl_lines="18"
{!> ../../docs_src/body_nested_models/tutorial006_py310.py!}
```

////

//// tab | Python 3.9+

 * 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.
 *

   * 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:
   *
   * <pre>{@code
   * 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>

    assertEquals(
        Types.subtypeOf(Object.class),
        TypeToken.of(Types.subtypeOf(Object[].class)).getComponentType().getType());
    assertEquals(
        Types.subtypeOf(Object[].class),
        Types.newArrayType(
            TypeToken.of(Types.subtypeOf(Object[].class)).getComponentType().getType()));
    assertEquals(
        int.class, TypeToken.of(Types.subtypeOf(int[].class)).getComponentType().getType());

    assertEquals(
        Types.subtypeOf(Object.class),
        TypeToken.of(Types.subtypeOf(Object[].class)).getComponentType().getType());
    assertEquals(
        Types.subtypeOf(Object[].class),
        Types.newArrayType(
            TypeToken.of(Types.subtypeOf(Object[].class)).getComponentType().getType()));
    assertEquals(
        int.class, TypeToken.of(Types.subtypeOf(int[].class)).getComponentType().getType());

      void visitClass(Class<?> t) {
        result.set(t.getComponentType());
      }
    }.visit(type);
    return result.get();
  }

  /**
   * Returns {@code ? extends X} if any of {@code bounds} is a subtype of {@code X[]}; or null
   * otherwise.
   */
  @CheckForNull
  private static Type subtypeOfComponentType(Type[] bounds) {
    for (Type bound : bounds) {
      Type componentType = getComponentType(bound);

    return create(AUDIO_TYPE, subtype);
  }

  /**
   * Creates a media type with the "font" type and the given subtype.
   *
   * @throws IllegalArgumentException if subtype is invalid
   */
  static MediaType createFontType(String subtype) {
    return create(FONT_TYPE, subtype);
  }

  /**
   * Creates a media type with the "image" type and the given subtype.
   *