[FIX] base_external_referentials : fix export resource when ids an empty tuple or an empty list
[FIX] base_external_referentials : fix export resource when ids an empty tuple or an empty list

esousy/connector,sylvain-garancher/connector,anybox/connector,brain-tec/connector,maljac/connector,BT-jmichaud/connector,zhaohuaw/connector,fevxie/connector,hugosantosred/connector,hugosantosred/connector,fevxie/connector,gurneyalex/connector,BT-ojossen/connector,js-landoo/connector,zhaohuaw/connector,brain-tec/connector,BT-fgarbely/connector,BT-fgarbely/connector,brain-tec/connector,MindAndGo/connector,maljac/connector,acsone/connector,mohamedhagag/connector,js-landoo/connector,Antiun/connector,BT-ojossen/connector,sylvain-garancher/connector,dvitme/connector,Endika/connector,guewen/connector,acsone/connector,mohamedhagag/connector,dvitme/connector,esousy/connector,MindAndGo/connector,anybox/connector,open-synergy/connector,BT-jmichaud/connector,Endika/connector,Antiun/connector,gurneyalex/connector,acsone/connector,open-synergy/connector,guewen/connector