Add java class for Ingress discard bpf map key value

Cherry-pick of aosp/2795708 to backport VPN security fix to non-mainline
U devices.

Bug: 193031925
Test: TH
Merged-In: Ic9ac423aee2a8fb9709b0acf012ec57cdfa019f9
Change-Id: Ib403099df5cefa3cbad52e3fd568b1a5047adcd4
2 files changed