Handler for initial data exchange between Ignite nodes. Data exchange
is initiated by a new node when it tries to join topology and finishes
before it actually joins.
Collects data from all components. This method is called both
on new node that joins topology to transfer its data to existing
nodes and on all existing nodes to transfer their data to new node.
Parameters:
dataBag - DiscoveryDataBag object managing discovery data during node joining process.