Fix return type in PHPDoc thanks to @jbostoen

Change to fit convention.

core/metamodel.class.php

@@ -7081,7 +7081,7 @@ abstract class MetaModel
 	 * @param array $aParams
 	 * @param bool $bAllowAllData
 	 *
-	 * @return \DBObject
+	 * @return \DBObject|null
 	 * @throws \OQLException
 	 */
 	public static function GetObjectFromOQL($sQuery, $aParams = null, $bAllowAllData = false)

sources/SessionTracker/iSessionHandlerExtension.php

@@ -2,6 +2,13 @@
 
 namespace Combodo\iTop\SessionTracker;
 
+	/**
+	 * @experimental for internal use only, subject to change without notice.
+	 *
+	 * Do not use this interface in your code.
+	 *
+	 * @since 3.2.2
+	 */
 interface iSessionHandlerExtension {
 	public function __construct();