Fix config type of SessionProviders

Bug: T307769
Change-Id: I88754b52c2fa69b6777ce6bee3825bfe97394e48

docs/config-schema.yaml

@@ -4614,15 +4614,15 @@ config-schema:
             active sessions (i.e. it will log everyone out).
             @since 1.27
     SessionProviders:
-        type: array
-        ignoreKeys: true
+        type: object
         default:
             MediaWiki\Session\CookieSessionProvider: { class: MediaWiki\Session\CookieSessionProvider, args: [{ priority: 30, callUserSetCookiesHook: true }] }
             MediaWiki\Session\BotPasswordSessionProvider: { class: MediaWiki\Session\BotPasswordSessionProvider, args: [{ priority: 75 }], services: [GrantsInfo] }
         description: |-
             MediaWiki\Session\SessionProvider configuration.
-            Values are ObjectFactory specifications for the SessionProviders
-            to be used. Keys in the array are ignored. Order is not significant.
+            Values are ObjectFactory specifications for the SessionProviders to be
+            used. Keys in the array are ignored; the class name is conventionally
+            used as the key to avoid collisions. Order is not significant.
             @since 1.27
     AllowRequiringEmailForResets:
         default: false

includes/MainConfigSchema.php

@@ -7111,14 +7111,14 @@ class MainConfigSchema {
 	/**
 	 * MediaWiki\Session\SessionProvider configuration.
 	 *
-	 * Values are ObjectFactory specifications for the SessionProviders
-	 * to be used. Keys in the array are ignored. Order is not significant.
+	 * Values are ObjectFactory specifications for the SessionProviders to be
+	 * used. Keys in the array are ignored; the class name is conventionally
+	 * used as the key to avoid collisions. Order is not significant.
 	 *
 	 * @since 1.27
 	 */
 	public const SessionProviders = [
-		'type' => 'list',
-		'ignoreKeys' => true,
+		'type' => 'map',
 		'default' => [
 			\MediaWiki\Session\CookieSessionProvider::class => [
 				'class' => \MediaWiki\Session\CookieSessionProvider::class,

includes/config-schema.php

@@ -2681,7 +2681,7 @@ return [
 				0 => 'string',
 				1 => 'null',
 			],
-			'SessionProviders' => 'array',
+			'SessionProviders' => 'object',
 			'AutoCreateTempUser' => 'object',
 			'BlockCIDRLimit' => 'object',
 			'EnablePartialActionBlocks' => 'boolean',
@@ -2945,9 +2945,6 @@ return [
 		'MaximalPasswordLength' => [
 			'deprecated' => 'since 1.26, use $wgPasswordPolicy\'s MaximalPasswordLength.',
 		],
-		'SessionProviders' => [
-			'ignoreKeys' => true,
-		],
 		'AllowRequiringEmailForResets' => [
 			'deprecated' => 'This feature is under development, don\'t assume this flag\'s existence or function outside of MediaWiki',
 		],