When registering a DataBroker Listener on a certain path, the initial data event should contain all pre-existing data.
In the case of a List node, the initial data event only contains one element instead of all elements.
For example:
"
container elan-instances {
list elan-instance {
...
"
When registering a listener on the path:
InstanceIdentifier.create(ElanInterfaces.class).child(ElanInterface.class))

the initial will only contain a single ElanInterface even though there are multiple ElanInterface's in the MD-SAL.