NetconfClientFactoryImpl should propagate stack failure
createClient() is ignoring failures to set up the transport stack,
leading to the future not completing on, for example, refused
connection.
Fix this by making ClientTransportChannelListener also a FutureCallback,
routing such failures to the returned future.
JIRA: NETCONF-1252
Change-Id: I3abc1faed94ee793ac6116eaca56a3cf473d8261
Signed-off-by: Oleksandr Zharov <oleksandr.zharov@pantheon.tech>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>