ImmutableList.Builder::add,
          ImmutableList.Builder::combine,
          ImmutableList.Builder::build);

  private static final Collector<Object, ?, ImmutableSet<Object>> TO_IMMUTABLE_SET =
      Collector.of(
          ImmutableSet::builder,
          ImmutableSet.Builder::add,
          ImmutableSet.Builder::combine,
          ImmutableSet.Builder::build);

  @GwtIncompatible

7. Here the `response_model` is using a type annotation of a list of `Author` dataclasses.

    Again, you can combine `dataclasses` with standard type annotations.

8. Notice that this *path operation function* uses regular `def` instead of `async def`.

    As always, in FastAPI you can combine `def` and `async def` as needed.

It will all be combined and included in your OpenAPI, and shown in the API docs:

<img src="/img/tutorial/additional-responses/image01.png">

## Combine predefined responses and custom ones

You might want to have some predefined responses that apply to many *path operations*, but you want to combine them with custom responses needed by each *path operation*.

    @RetainedLocalRef List<@Nullable Present<V>> localValues = values;
    if (localValues != null) {
      set(combine(localValues));
    }
  }

  @Override
  void releaseResources(ReleaseResourcesReason reason) {
    super.releaseResources(reason);
    this.values = null;
  }

  abstract C combine(List<@Nullable Present<V>> values);

  /** Used for {@link Futures#allAsList} and {@link Futures#successfulAsList}. */

        <configuration>
          <defaults><!-- equivalent to combine.children="merge" combine.self="merge" -->
            <!-- merge the content of the configuration element according to element name -->
            <parent>child</parent>
            <child>child</child>
            <parent-only>parent</parent-only>
          </defaults>
          <appends combine.children="append">
            <parent-only>parent</parent-only>

  }

  /**
   * A generic {@link Combiner} that lets you use a lambda or method reference to combine two {@link
   * ClosingFuture}s. Use {@link #whenAllSucceed(ClosingFuture, ClosingFuture)} to start this
   * combination.
   *
   * @param <V1> the type returned by the first future
   * @param <V2> the type returned by the second future
   */

        uses: actions/upload-artifact@v4
        with:
          name: coverage-${{ matrix.python-version }}-${{ matrix.pydantic-version }}
          path: coverage
          include-hidden-files: true

  coverage-combine:
    needs: [test]
    runs-on: ubuntu-latest
    steps:
      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"

		},
		cli.BoolFlag{
			Usage: "combine inline data",
			Name:  "combine",
		},
		cli.BoolFlag{
			Usage: "combine inline data across versions when size matches",
			Name:  "xver",
		},
	}

	app.Action = func(c *cli.Context) error {
		ndjson := c.Bool("ndjson")
		if c.Bool("data") && c.Bool("combine") {
			return errors.New("cannot combine --data and --combine")
		}
		// file / version / file

          <defaults>
            <parent>child</parent>
            <child>child</child>
          </defaults>
          <appends combine.children="append">
            <parent>child</parent>
            <child>child</child>
          </appends>
          <overrides combine.self="override">
            <parent>child</parent>
            <child>child</child>
          </overrides>
        </configuration>
      </plugin>

   */
  private static final Collector<Object, ?, Optional<Object>> TO_OPTIONAL =
      Collector.of(
          ToOptionalState::new,
          ToOptionalState::add,
          ToOptionalState::combine,
          ToOptionalState::getOptional,
          Collector.Characteristics.UNORDERED);

  /**
   * A collector that converts a stream of zero or one elements to an {@code Optional}.
   *