}

func TestHeadersAlreadyWritten(t *testing.T) {
	rw := httptest.NewRecorder()
	trw := &trackingResponseWriter{ResponseWriter: rw}

	if headersAlreadyWritten(trw) {
		t.Fatal("headers have not been written yet")
	}

	trw.WriteHeader(123)
	if !headersAlreadyWritten(trw) {
		t.Fatal("headers were written")
	}
}

func TestHeadersAlreadyWrittenWrapped(t *testing.T) {
	rw := httptest.NewRecorder()

 * limitations under the License.
 */
package okhttp3

import okio.IOException

/**
 * Returns the trailers that follow an HTTP response, blocking if they aren't ready yet.
 * Implementations of this interface should respond to [Call.cancel] by immediately throwing an
 * [IOException].
 *
 * Most callers won't need this interface, and should use [Response.trailers] instead.
 *

// if configured.
func ReadinessCheckHandler(w http.ResponseWriter, r *http.Request) {
	if objLayer := newObjectLayerFn(); objLayer == nil {
		w.Header().Set(xhttp.MinIOServerStatus, unavailable) // Service not initialized yet
	}
	if r.Header.Get(xhttp.MinIOPeerCall) != "" {
		writeResponse(w, http.StatusOK, nil, mimeNone)
		return
	}

	if int(globalHTTPStats.loadRequestsInQueue()) > globalAPIConfig.getRequestsPoolCapacity() {

/**
 * Do not use!
 * <p>
 * Should only be implemented by DebugResolutionListener.  Remove this
 * when the ResolutionListener interface deprecation of the manageArtifact
 * method (and the [yet to be done] addition of these methods to that
 * interface) has had a chance to propagate to all interested plugins.
 */
@Deprecated
public interface ResolutionListenerForDepMgmt {

import static java.util.Objects.requireNonNull;

/**
 * System {@link Logger}. Uses provided {@link PrintStream}s or {@link System#err} ones as fallback.
 * This logger is used in case of "early failures" (when no logging may be set up yet).
 */
public class SystemLogger implements Logger {
    private final PrintWriter out;
    private final Level threshold;

    public SystemLogger(@Nullable OutputStream out) {
        this(out, null);
    }

/**
 * Partial identification of an {@link Artifact} in a Maven repository.
 * Each {@code ArtifactCoordinates} instance is basically a pointer to a file in the Maven repository,
 * except that the exact version may not be known yet.
 *
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface ArtifactCoordinates {
    /**
     * {@return the group identifier of the artifact}.
     */
    @Nonnull
    String getGroupId();

          .that(returnType.getComponentType())
          .isEqualTo(annotationClass.getDeclaringClass());
    }
  }

  // This is public so that tests for Feature enums we haven't yet imagined
  // can reuse it.
  public static <E extends Enum<?> & Feature<?>> void assertGoodFeatureEnum(
      Class<E> featureEnumClass) {
    Class<?>[] classes = featureEnumClass.getDeclaredClasses();

        // We need to set the file here or the resolver will fail with an NPE, not fully equipped to deal
        // with multiple local repository implementations yet.
        artifact.setFile(artifactFile);

        return artifact;
    }

    @Override
    public String getId() {
        return localRepository.getId();
    }

    @Override

/**
 * Early CLI {@link Logger} that simply accumulates log entries until some point a real logger can emit them. This
 * logger is created at start, and it exists while no logging is available yet.
 */
public class AccumulatingLogger implements Logger {
    private final AtomicReference<List<Entry>> entries = new AtomicReference<>(new CopyOnWriteArrayList<>());

    @Override

///

## Returning a custom `Response` { #returning-a-custom-response }

The example above shows all the parts you need, but it's not very useful yet, as you could have just returned the `item` directly, and **FastAPI** would put it in a `JSONResponse` for you, converting it to a `dict`, etc. All that by default.

Now, let's see how you could use that to return a custom response.