Merge "Make NattKeepalivePacketData @SystemApi" am: 9fef5a5cf0 am: 6426059fa3

Change-Id: If93d5bacd85fa5209f3fbb55d1cf0af1231e605d
tree: eeade3b23c48806b04f368556677d075ea16f890
  1. core/
  2. services/
  3. tests/