fix(IMimeTypeDetector): use correct return type

lib/private/Files/Type/Detection.php

@@ -23,7 +23,7 @@ class Detection implements IMimeTypeDetector {
 	private const CUSTOM_MIMETYPEMAPPING = 'mimetypemapping.json';
 	private const CUSTOM_MIMETYPEALIASES = 'mimetypealiases.json';
 
-	/** @var array<string, list{string, string|null}> */
+	/** @var array<list{string, string|null}> */
 	protected array $mimetypes = [];
 	protected array $secureMimeTypes = [];
 
@@ -140,7 +140,7 @@ private function loadMappings(): void {
 	}
 
 	/**
-	 * @return array<string, list{string, string|null}>
+	 * @return array<list{string, string|null}>
 	 */
 	public function getAllMappings(): array {
 		$this->loadMappings();

lib/public/Files/IMimeTypeDetector.php

@@ -75,7 +75,15 @@ public function mimeTypeIcon($mimeType);
 	public function getAllAliases(): array;
 
 	/**
-	 * @return array<string, list{string, string|null}>
+	 * Get all extension to MIME type mappings.
+	 *
+	 * The return format is an array of the file extension, as the key,
+	 * mapped to a list where the first entry is the MIME type
+	 * and the second entry is the secure MIME type (or null if none).
+	 * Due to PHP idiosyncrasies if a numeric string is set as the extension,
+	 * then also the array key (file extension) is a number instead of a string.
+	 *
+	 * @return array<list{string, string|null}>
 	 * @since 32.0.0
 	 */
 	public function getAllMappings(): array;