*: drop subnet support

We don't need them and while there are reason to have some remnants in the
protocol itself we can remove them from the SDK immediately to not include
them into the 1.0.0 release.

Refs. nspcc-dev/neofs-api#261.

container/container.go

@@ -15,7 +15,6 @@ import (
 	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
 	neofscrypto "github.com/nspcc-dev/neofs-sdk-go/crypto"
 	"github.com/nspcc-dev/neofs-sdk-go/netmap"
-	subnetid "github.com/nspcc-dev/neofs-sdk-go/subnet/id"
 	"github.com/nspcc-dev/neofs-sdk-go/user"
 	"github.com/nspcc-dev/neofs-sdk-go/version"
 )
@@ -116,8 +115,6 @@ func (x *Container) readFromV2(m container.Container, checkFieldPresence bool) e
 		}
 
 		switch key {
-		case container.SysAttributeSubnet:
-			err = new(subnetid.ID).DecodeString(val)
 		case attributeTimestamp:
 			_, err = strconv.ParseInt(val, 10, 64)
 		}
@@ -381,28 +378,6 @@ func CreatedAt(cnr Container) time.Time {
 	return time.Unix(sec, 0)
 }
 
-// SetSubnet places the Container on the specified NeoFS subnet. If called,
-// container nodes will only be selected from the given subnet, otherwise from
-// the entire network.
-func SetSubnet(cnr *Container, subNet subnetid.ID) {
-	cnr.SetAttribute(container.SysAttributeSubnet, subNet.EncodeToString())
-}
-
-// Subnet return container subnet set using SetSubnet.
-//
-// Zero Container is bound to zero subnet.
-func Subnet(cnr Container) (res subnetid.ID) {
-	val := cnr.Attribute(container.SysAttributeSubnet)
-	if val != "" {
-		err := res.DecodeString(val)
-		if err != nil {
-			panic(fmt.Sprintf("invalid subnet attribute: %s (%v)", val, err))
-		}
-	}
-
-	return
-}
-
 const attributeHomoHashEnabled = "true"
 
 // DisableHomomorphicHashing sets flag to disable homomorphic hashing of the

container/container_test.go

@@ -17,8 +17,6 @@ import (
 	neofscrypto "github.com/nspcc-dev/neofs-sdk-go/crypto"
 	"github.com/nspcc-dev/neofs-sdk-go/crypto/test"
 	netmaptest "github.com/nspcc-dev/neofs-sdk-go/netmap/test"
-	subnetid "github.com/nspcc-dev/neofs-sdk-go/subnet/id"
-	subnetidtest "github.com/nspcc-dev/neofs-sdk-go/subnet/id/test"
 	usertest "github.com/nspcc-dev/neofs-sdk-go/user/test"
 	"github.com/nspcc-dev/neofs-sdk-go/version"
 	"github.com/stretchr/testify/require"
@@ -233,28 +231,6 @@ func TestSetCreationTime(t *testing.T) {
 	require.Equal(t, creat.Unix(), container.CreatedAt(val2).Unix())
 }
 
-func TestSetSubnet(t *testing.T) {
-	var val container.Container
-
-	require.True(t, subnetid.IsZero(container.Subnet(val)))
-
-	val = containertest.Container(t)
-
-	sub := subnetidtest.ID()
-
-	container.SetSubnet(&val, sub)
-
-	var msg v2container.Container
-	val.WriteToV2(&msg)
-
-	assertContainsAttribute(t, msg, v2container.SysAttributeSubnet, sub.EncodeToString())
-
-	var val2 container.Container
-	require.NoError(t, val2.ReadFromV2(msg))
-
-	require.Equal(t, sub, container.Subnet(val))
-}
-
 func TestDisableHomomorphicHashing(t *testing.T) {
 	var val container.Container