Access to the requested URI has been blocked by the URL Firewall.
If you believe that you have reached this page while performing valid operations within the application, please send mail to firstname.lastname@example.org explaining what you were doing when you got this error.
This is expected because the url firewall file doesn't have this entry. To allow this we made the following change indicated in bold in the $IAS_ORACLE_HOME/Apache/Apache/conf/url_fw.conf file present on the extranet web tiers:
On line 617 of url_fw.conf:
#Include all Custom files
# Third party link
RewriteRule https://www.thirdpartysite.com - [L]
# If not allowed by list above - go away! [G] is '410 Gone'
RewriteRule .* - [G]
# END Positive list of URLs
After making this change, the Gone error stopped coming.