In Apache 2.x things are different. A module can handle different stages of the request, such as URL fixup.mod_dir handles this stage by redirecting a request (when the URL maps to a directory) to the URL with a/ appended.
Dispatcher does not intercept the mod_dir fixup, but completely handles the request to the redirected URL (i.e. with / appended). This might pose a problem if the remote server (e.g. AEM) handles requests to/a_path differently to requests to /a_path/ (when /a_path maps to an existing directory).
If this happens you must either:
- disable mod_dir for the Directory or Location subtree handled by the dispatcher
- use DirectorySlash Off to configure mod_dir not to append /