When I run the fido demo, then click google to log in, select an account, and report this error after logging in successfully：
com.fido.example.fido2apiexample E/GAEService: Error getting all security key tokens
com.google.api.client.googleapis.json.GoogleJsonResponseException: 404 Not Found



404 Page not found

Error: Page not found

The requested URL was not found on this server.

at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:113)
at com.google.api.client.googleapis.services.json.AbstractGoogleJsonClientRequest.newExceptionOnError(AbstractGoogleJsonClientRequest.java:40)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$1.interceptResponse(AbstractGoogleClientRequest.java:321)
at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:1067)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:419)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:352)
at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:469)
at com.fido.example.fido2apiexample.GAEService.getAllSecurityTokens(GAEService.java:343)
at com.fido.example.fido2apiexample.Fido2DemoActivity$15.call(Fido2DemoActivity.java:565)
at com.fido.example.fido2apiexample.Fido2DemoActivity$15.call(Fido2DemoActivity.java:561)
at com.google.android.gms.tasks.zzv.run(Unknown Source:2)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1137)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:637)
at java.lang.Thread.run(Thread.java:1012)

Reproduce the flow in the fido demo, then inspect GAEService.getAllSecurityTokens at GAEService.java:343 and its caller in Fido2DemoActivity.java:561-565. Trace the request that returns 404 and verify the Google login and security-token path. Done means the account-selection flow no longer reports this 404 and security tokens load successfully.

Written by the indexing model from the issue text.