Merge "Speed up the DHCP roaming tests." am: b2ff3ca8

        doAnswer(invocation -> {

            // we don't rely on the Init-Reboot state to renew previous cached IP lease.

            // Just return null and force state machine enter INIT state.

            final String l2Key = invocation.getArgument(0);

            ((OnNetworkAttributesRetrievedListener) invocation.getArgument(1))

                    .onNetworkAttributesRetrieved(new Status(SUCCESS), l2Key, null);

            return null;

        }).when(mIpMemoryStore).retrieveNetworkAttributes(eq(TEST_L2KEY), any());