c51a705a45
As the review feedback, this commits address below concern. 1. The TCP keepalive code doesn't use the network parameter at all. This parameter doesn't seem meaningful for TCP keepalives. Starting a TCP keepalive with a non-null underpinned network should throw IllegalArgumentException. 2. The feedback mention that the start version which takes a @NonNull network should throw NPE if the network is null. But Starting a NATT keepalive does not always require a underpinned network. A new IkeSession started from Vpn will also not assign the underpinned network at the initial stage which means underpinned will be null until setNetwork() is called. Thus, the underpinned network should be @Nullable instead. Fix: 271797087 Test: atest FrameworksNetTests Change-Id: Ieb57a7b15a06b2ccd94358b65cc00768c4f62e7d