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.

from fastapi import Depends, FastAPI

app = FastAPI()


def get_username():
    try:
        yield "Rick"
    finally:
        print("Cleanup up before response is sent")


@app.get("/users/me")
def get_user_me(username: str = Depends(get_username, scope="function")):

import org.lastaflute.web.api.ApiFailureHook;
import org.lastaflute.web.api.ApiFailureResource;
import org.lastaflute.web.login.exception.LoginUnauthorizedException;
import org.lastaflute.web.response.ApiResponse;
import org.lastaflute.web.response.JsonResponse;

/**
 * The hook for API failure.
 *
 * @author jflute
 */
public class FessApiFailureHook implements ApiFailureHook { // #change_it for handling API failure

Pobres banners de cookies con todo su esfuerzo para obtener tu consentimiento para que la <abbr title="Esta es otra broma. No me prestes atención. Toma un café para tu cookie. ☕">API lo rechace</abbr>. 🍪

     * If an error occurs during execution, it will be cached and re-thrown for subsequent identical requests.
     *
     * @param <REQ> The request type
     * @param <REP> The response type
     * @param req The request object used as the cache key
     * @param supplier The function to execute and cache the result
     * @return The result from the supplier (either fresh or cached)

    /** The key of the configuration. e.g. 50 */
    String RESPONSE_MAX_TITLE_LENGTH = "response.max.title.length";

    /** The key of the configuration. e.g. 100 */
    String RESPONSE_MAX_SITE_PATH_LENGTH = "response.max.site.path.length";

    /** The key of the configuration. e.g. true */

    @Override
    public Logger getLogger() {
        return logger;
    }

    /**
     * Gets the appropriate extractor for the given response data.
     * Selects an extractor based on the MIME type or falls back to the Tika extractor.
     *
     * @param responseData the response data containing the document to extract
     * @return the extractor instance for processing the document

 *
 * <p>This interface is intended for internal use.</p>
 */
public enum RequestParam {

    /**
     * No special request parameters.
     */
    NONE,

    /**
     * Wait indefinitely for a response
     */
    NO_TIMEOUT,

    /**
     * Do not retry request on failure
     */
    NO_RETRY,

    /**
     * Save the raw payload for further inspection
     */
    RETAIN_PAYLOAD