Merge remote-tracking branch 'origin/master' into feature/ipv6_support

protocols/bgp/packet/bgp.go

protocols/bgp/packet/decoder_test.go

protocols/bgp/packet/path_attributes.go

protocols/bgp/packet/path_attributes_test.go

protocols/bgp/server/BUILD.bazel

protocols/bgp/server/fsm_established.go

protocols/bgp/server/update_sender.go

protocols/bgp/server/update_sender_test.go

protocols/bgp/types/BUILD.bazel

protocols/bgp/types/aggregator.go

route/bgp_path.go

testing/conn_mock.go