Resolve "(CTTC) Context component's Link attribute `used_capacity_gbps` is wrongly managed"

Closes #97 (closed)

src/context/service/database/Link.py

@@ -102,14 +102,17 @@ def link_set(db_engine : Engine, messagebroker : MessageBroker, request : Link)
     total_capacity_gbps, used_capacity_gbps = None, None
     if request.HasField('attributes'):
         attributes = request.attributes
+
         # In proto3, HasField() does not work for scalar fields, using ListFields() instead.
         attribute_names = set([field.name for field,_ in attributes.ListFields()])
+
         if 'total_capacity_gbps' in attribute_names:
             total_capacity_gbps = attributes.total_capacity_gbps
+
         if 'used_capacity_gbps' in attribute_names:
             used_capacity_gbps = attributes.used_capacity_gbps
-        elif total_capacity_gbps is not None:
-            used_capacity_gbps = total_capacity_gbps
+        else:
+            used_capacity_gbps = 0.0
 
     link_data = [{
         'link_uuid'           : link_uuid,