WidgetService 26.8.0 API

All Implemented Interfaces:
```
public final class WidgetService
extends MobileService
                    
```
Provides widget-scoped HTTP access to BTP mobile services using the host app's OAuth token and a session-first authentication strategy. Replaces AppExtensionService.
Token confidentiality is layered:
- The on-disk token blob is AES-256-GCM encrypted (RawEncryption).
- The encryption key is derived per-call as keystoreKey XOR localNonce, where keystoreKey comes from EncryptionUtil (Android Keystore) and localNonce is a 32-byte per-install random persisted in WidgetNonceStore (EncryptedSharedPreferences).
- All key copies are zeroed in finally immediately after the cryptographic operation.
Usage:
```
val services = mutableListOf<MobileService>()
services.add(WidgetService())
SDKInitializer.start(application = application, services = services.toTypedArray())
```

Nested Class Summary

Nested Classes
Modifier and Type	Class	Description

Field Summary

Fields
Modifier and Type	Field	Description
`private Application`	`application`
`private String`	`apiKey`

Constructor Summary

Constructors
Constructor	Description
`WidgetService(CoroutineDispatcher ioDispatcher)`
`WidgetService()`

Enum Constant Summary

Enum Constants
Enum Constant	Description

Method Summary

Modifier and Type	Method	Description
`Unit`	`init(Application application, String apiKey)`	Initializes the mobile service
`Unit`	`onStateChange(ApplicationState state)`	Notified when application state changes.
`final OkHttpClient`	`buildHttpClient(Function1<List<AbstractOAuthClient>, AbstractOAuthClient> clientFilter, Function1<OkHttpClient.Builder, Unit> configure)`	Builds an OkHttpClient configured for widget read-only access.
`Unit`	`reset()`	Resets the mobile service to the state that just initialized.

Methods inherited from class com.sap.cloud.mobile.foundation.mobileservices.MobileService
enableNetworkPolicy, getApiKey, getApplication, isApplicationInitialized, mayStartNewProcess, setApiKey, setApplication
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - WidgetService
```
WidgetService(CoroutineDispatcher ioDispatcher)
```
  - WidgetService
```
WidgetService()
```
- Method Detail
  - init
```
 Unit init(Application application, String apiKey)
```
    Initializes the mobile service
  - onStateChange
```
 Unit onStateChange(ApplicationState state)
```
    Notified when application state changes. This function will be called on Main thread.
  - buildHttpClient
```
 final OkHttpClient buildHttpClient(Function1<List<AbstractOAuthClient>, AbstractOAuthClient> clientFilter, Function1<OkHttpClient.Builder, Unit> configure)
```
    Builds an OkHttpClient configured for widget read-only access.
    The client uses a session-first authentication strategy: requests are first sent with session cookies; on 401, the client falls back to Bearer token authentication with automatic token refresh.
    
    Parameters:
    
    clientFilter - optional filter to select which OAuth client to use from the configured list.
    
    configure - optional block to further customize the OkHttpClient.Builder (e.g.
    
    Returns:
    
    a configured OkHttpClient, or null if the service is not ready (missing AppConfig, user, or OAuth configuration).
  - reset
```
 Unit reset()
```
    Resets the mobile service to the state that just initialized.