Javadoc
Identify an existing EPerson based upon the shibboleth attributes provided on
the request object. There are three cases where this can occurr, each as
a fallback for the previous method.
1) NetID from Shibboleth Header (best)
The NetID-based method is superior because users may change their email
address with the identity provider. When this happens DSpace will not be
able to associate their new address with their old account.
2) Email address from Shibboleth Header (okay)
In the case where a NetID header is not available or not found DSpace
will fall back to identifying a user based upon their email address.
3) Tomcat's Remote User (worst)
In the event that neither Shibboleth headers are found then as a last
resort DSpace will look at Tomcat's remote user field. This is the least
attractive option because Tomcat has no way to supply additional
attributes about a user. Because of this the autoregister option is not
supported if this method is used.
If successful then the identified EPerson will be returned, otherwise null.