[FIX] base_external_referentials : fix import/export of sub_mapping
[FIX] base_external_referentials : fix import/export of sub_mapping

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