...
Added a <security-constraint> to the web.xml and redeployed. Result: I get a "500 Internal Server Error" error when I click on the servlet link. In the appengine control panel error log I see the message:
"Authentication for the Google Apps domain sagebionetworks.com can only be performed when requests are served from a subdomain of that domain or it has been approved through the Google Apps Control Panel."
I logged in using my sagebionetworks.com credentials, but got the same error again.
Notes
Q: What's the cumulative file size on the Sage SSH server?
...