Internationalization: set default language

[Francesco Malvezzi]

hi everybody,

while upgrading to shibboleth-idp-4.2.1 I messed up the i14n in the 
login view.

Now it serves (mostly) a single language.

'Mostly' means that login view recognizes browser's header 
accept-encoding but looks for translation only in $IDP_HOME/messages/ 
directory, where I store the overrides.

If a message key (say idp.login.donotcache) it's not found there, it 
gets the Italian system file by default.

My $IDP_HOME/system/ has no 'messages' directory as it should be.

The $IDP_HOME/conf/services.xml contains:

<util:list id="shibboleth.MessageSourceResources">
     <value>%{idp.home}/messages/messages</value>
</util:list>

and $IDP_HOME/conf/idp.properties:

idp.ui.fallbackLanguages= en

but still:

https://idp3.unimore.it/idp/profile/admin/hello

(please note the idp.attribute-release.revoke message text which is 
present in $IDP_HOME/messages/messages_en.properties and correctly served).

What did I overlook?

thank you so much,

Francesco