Confluence 4.0.x does not update LOGININFO correctly when using custom authenticator

Confluence supports use of custom authenticators in Confluence 4.0.x, but when using a custom authenticator, a customer reports that the LOGININFO table is not being updated.

It is unclear to me what must be done in the custom authenticator to ensure that LOGININFO is updated successfully when using our custom authenticator.
(Please add Erkki Aalto to ticket who is customer having this issue.)

This is not a request for assistance with the authenticator or in developing it, but a question of whether this is a bug in Confluence 4.0.x/Embedded Crowd when used with custom authenticators in-general, or whether the documentation for developing Confluence custom authenticators could include a brief summary of how to use Atlassian APIs in a custom Confluence authenticator to ensure that this LOGININFO table can be updated properly for user login auditing functionality that is assumed to be supported in Confluence 4.0.

If this turns out to be a support issue, I apologize in advance. Basically, it would be nice if someone with familiarity in this part of Confluence/Embedded Crowd can ensure that this should work properly even when a custom Confluence authenticator is in use and that nothing special has to be done in the authenticator for it to work, especially considering that Erkki has posted a log fragment showing that Confluence does indeed attempt to update the table.

This issue has been documented in this two locations:
https://answers.atlassian.com/questions/21460/how-to-update-logininfo-table-in-confluence-4-0-in-custom-confluence-authenticator
https://studio.plugins.atlassian.com/browse/SHBL-50