correct sample default expression to detect XML HTTP Requests
# to return 401 for requests in an iframe or requests that load an image:
# OIDCUnAuthAction 401 "%{HTTP:Sec-Fetch-Dest} == 'iframe' || %{HTTP:Sec-Fetch-Dest} == 'image'"
# or just as a more complex example, which equals the default XML request detection algorithm:
-# OIDCUnAuthAction 401 "%{HTTP:X-Requested-With} == 'XMLHttpRequest' || %{HTTP:Sec-Fetch-Mode} != 'navigate' || ( ( %{HTTP_ACCEPT} !~ m#text/html# ) && ( %{HTTP_ACCEPT} !~ m#application/xhtml\+xml# ) && ( %{HTTP_ACCEPT} !~ m#\*/\*# ) )"
+# OIDCUnAuthAction 401 "%{HTTP:X-Requested-With} == 'XMLHttpRequest' || ( -n %{HTTP:Sec-Fetch-Mode} && %{HTTP:Sec-Fetch-Mode} != 'navigate' ) || ( ( %{HTTP_ACCEPT} !~ m#text/html# ) && ( %{HTTP_ACCEPT} !~ m#application/xhtml\+xml# ) && ( %{HTTP_ACCEPT} !~ m#\*/\*# ) )"
# To disable auto-detection of XML HTTP request altogether and uncondtionally return "auth" for all clients:
# OIDCUnAuthAction auth true
# Note that actually *any* expression value in "OIDCUnAuthAction auth <expr>" will *always* render "auth"
