Test if underlying networks are the same as what VpnService sets

If VpnService set null as the underlying networks, then the
underlying networks will be set as system defeult network.
If VpnService set an empty array as the underlying networks, then
the underlying networks of VPN will not be set to any networks.
If VpnService set a network which is not null or an empty array,
then the underlying networks of VPN should be the same as this
one.

Bug: 191918368
Test: atest CtsHostsideNetworkTests:HostsideVpnTests
Change-Id: Ib2d54e53960e5f899cb8d4cfaa6705ca676354ca
1 file changed