}

        @Test
        @DisplayName("Should combine referral data")
        void testCombine() {
            DfsReferralDataInternal combined = mock(DfsReferralDataInternal.class);

            // Test with mock
            when(mockReferralData.combine(mockDfsReferralData)).thenReturn(combined);
            DfsReferralDataInternal result = mockReferralData.combine(mockDfsReferralData);
            assertSame(combined, result);

          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

          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

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 { #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*.

  }

  /**
   * 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
   */

		},
		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

     */
    boolean isIntermediate();

    /**
     * Combine this referral with another to form a chain
     *
     * @param next the referral to combine with
     * @return new referral, combining a chain of referrals
     */
    DfsReferralDataInternal combine(DfsReferralData next);

    /**
     * Append another referral to this referral chain
     *

        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"

    @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}. */

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.