Merge "Update AppFunction Documentation" into main

import java.util.function.Consumer;

/**

 * Provides app functions related functionalities.

 * Provides access to app functions.

 *

 * <p>App function is a specific piece of functionality that an app offers to the system. These

 * functionalities can be integrated into various system features.

 * <p>An app function is a piece of functionality that apps expose to the system for cross-app

 * orchestration.

 *

 * <p>**Developer Workflow:**

 *

 * <p>Most developers should interact with app functions through the AppFunctions SDK. This SDK

 * library offers a more convenient and type-safe way to represent the inputs and outputs of an app

 * function, using custom data classes called "AppFunction Schemas".

 *

 * <p>The suggested way to build an app function is to use the AppFunctions SDK. The SDK provides

 * custom data classes (AppFunctions Schemas) and handles the conversion to the underlying {@link

 * android.app.appsearch.GenericDocument}/{@link android.os.Bundle} format used in {@link

 * ExecuteAppFunctionRequest} and {@link ExecuteAppFunctionResponse}.

 *

 * <p>**Discovering (Listing) App Functions:**

 *

 * <p>When there is a package change or the device starts up, the metadata of available functions is

 * indexed on-device by {@link AppSearchManager}. AppSearch stores the indexed information as a

 * {@code AppFunctionStaticMetadata} document. This allows other apps and the app itself to discover

 * these functions using the AppSearch search APIs. Visibility to this metadata document is based on

 * the packages that have visibility to the app providing the app functions.

 *

 * <p>**Executing App Functions:**

 *

 * <p>Requests to execute a function are built using the {@link ExecuteAppFunctionRequest} class.

 * Callers need the {@code android.permission.EXECUTE_APP_FUNCTIONS} or {@code

 * android.permission.EXECUTE_APP_FUNCTIONS_TRUSTED} permission to execute app functions from other

 * apps. An app has automatic visibility to its own functions and doesn't need these permissions to

 * call its own functions via {@code AppFunctionManager}.

 */

@FlaggedApi(FLAG_ENABLE_APP_FUNCTION_MANAGER)

@SystemService(Context.APP_FUNCTION_SERVICE)