As mentioned in the new features section the following properties having been transformed in configurations, so they are no longer available in the properties files:
session.timeout.auto.extendsession.timeout.auto.extend.offset
Release Notes
このセクションには、DXPの機能および性能の重大な変更点に関する情報が含まれています。重大な変更点または内部コードについては、こちらのリンクをご覧ください。
The configuration sections in Utility Pages are not enabled, as the other pages, due to their use being more restricted. The implementation of these settings should occur by analyzing each case.