final CommonServerMessageBlock response) {
        if (log.isTraceEnabled()) {
            log.trace("Signing with seq " + this.signSequence);
        }

        ((ServerMessageBlock) request).setSignSeq(this.signSequence);
        if (response != null) {
            ((ServerMessageBlock) response).setSignSeq(this.signSequence + 1);
        }

        try {

    private static final int SMB2_HEADER_LENGTH = 64;

    /**
     * Build a minimal SMB2 header for a response.
     */
    private static byte[] buildSmb2Header() {
        byte[] header = Arrays.copyOf(SMBUtil.SMB2_HEADER, SMBUtil.SMB2_HEADER.length);
        // Mark as server->client response for realism
        SMBUtil.writeInt4(0x00000001, header, 16); // Flags
        // Command SMB2_CREATE (0x0005)

    }

    /**
     * Helper method to mock the response of an HttpURLConnection.
     */
    private void mockResponse(int code, String message, Map<String, List<String>> headers, InputStream errorStream) throws IOException {
        mockResponse(this.mockConnection, code, message, headers, errorStream);
    }

    /**
     * Helper method to mock the response of a specific HttpURLConnection instance.
     */

In this case, you could want to document how that external API *should* look like. What *path operation* it should have, what body it should expect, what response it should return, etc.

## An app with callbacks { #an-app-with-callbacks }

Let's see all this with an example.

Imagine you develop an app that allows creating invoices.

    * FastAPI는 Starlette에 추가적으로 더 많은 기능을 제공합니다. API를 구축할 때 거의 항상 필요한 데이터 검증 및 직렬화와 같은 기능들이 포함되어 있습니다. 그리고 이를 사용하면 문서 자동화 기능도 제공됩니다(문서 자동화는 응용 프로그램 실행 시 오버헤드를 추가하지 않고 시작 시 생성됩니다).
    * FastAPI를 사용하지 않고 직접 Starlette(또는 Sanic, Flask, Responder 등)를 사용했다면 데이터 검증 및 직렬화를 직접 구현해야 합니다. 따라서 최종 응용 프로그램은 FastAPI를 사용한 것과 동일한 오버헤드를 가지게 될 것입니다. 많은 경우 데이터 검증 및 직렬화가 응용 프로그램에서 작성된 코드 중 가장 많은 부분을 차지합니다.

	checkPartFileNotFound
	checkPartFileCorrupt
)

// CheckPartsResp is a response of the storage CheckParts and VerifyFile APIs
type CheckPartsResp struct {
	Results []int `msg:"r"`
}

// LocalDiskIDs - GetLocalIDs response.
type LocalDiskIDs struct {
	IDs []string `msg:"i"`
}

// ListDirResult - ListDir()'s response.
type ListDirResult struct {
	Entries []string `msg:"e"`
}

  return result.build()
}

private fun PushPromise.wrap(): mockwebserver3.PushPromise =
  mockwebserver3.PushPromise(
    method = method,
    path = path,
    headers = headers,
    response = response.wrap(),
  )

internal fun mockwebserver3.RecordedRequest.unwrap(): RecordedRequest =
  RecordedRequest(
    requestLine = requestLine,
    headers = headers,
    chunkSizes = chunkSizes ?: listOf(),

     */
    @Override
    public void doFilter(final ServletRequest request, final ServletResponse response, final FilterChain chain)
            throws IOException, ServletException {
        final HttpServletRequest req = (HttpServletRequest) request;
        final HttpServletResponse resp = (HttpServletResponse) response;
        NtlmPasswordAuthentication ntlm = negotiate(req, resp, false);

        if (ntlm == null) {

            builderLambda.accept(builder);
            final UpdateResponse response = builder.execute().actionGet(fessConfig.getIndexIndexTimeout());
            return response.getResult() == Result.CREATED || response.getResult() == Result.UPDATED;
        } catch (final OpenSearchException e) {
            throw new SearchEngineClientException("Failed to update doc  " + id, e);

			ParentUser:   tmpCredentials.ParentUser,
		},
		UpdatedAt: updatedAt,
	}))

	response := new(AssumeRoleWithCustomTokenResponse)
	response.Result.Credentials = tmpCredentials
	response.Result.AssumedUser = parentUser
	response.Metadata.RequestID = w.Header().Get(xhttp.AmzRequestID)
	writeSuccessResponseXML(w, encodeResponse(response))