I upgraded LS 3.4 to LS 3.6, On subscribing from client, LS was showing message "Refused request: Requested nonexistent default Data Adapter for ION2 from"

since in client adapter name has not been set , yet with LS 3.4 it work fine.

does it mean LS3.4 assume a default adapter and LS 3.6 need explicitly adapter name?
Is there a way to configure default adapter name in adapter.xml for LS 3.6 so that LS client only need to mentioned adapters_conf id and can leave to set adapter name?