[#72] session: Unify unmarshaling code

gopatch:
```
@@
var err, msg, data, t, protojson identifier
var obj expression
@@
+import "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/message"
-import protojson "google.golang.org/protobuf/encoding/protojson"

-msg := obj
-if err := protojson.Unmarshal(data, msg); err != nil {
-return err
-}
-return t.FromGRPCMessage(msg)
+return message.UnmarshalJSON(t, data, obj)

@@
var err, msg, data, t, goproto identifier
var obj expression
@@
+import "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/message"
-import goproto "google.golang.org/protobuf/proto"

-msg := obj
-if err := goproto.Unmarshal(data, msg); err != nil {
-return err
-}
-return t.FromGRPCMessage(msg)
+return message.Unmarshal(t, data, obj)
```

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

session/json.go

@@ -3,7 +3,6 @@ package session
 import (
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/message"
 	session "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session/grpc"
-	"google.golang.org/protobuf/encoding/protojson"
 )
 
 func (c *ObjectSessionContext) MarshalJSON() ([]byte, error) {
@@ -27,13 +26,7 @@ func (t *TokenBody) MarshalJSON() ([]byte, error) {
 }
 
 func (t *TokenBody) UnmarshalJSON(data []byte) error {
-	msg := new(session.SessionToken_Body)
+	return message.UnmarshalJSON(t, data, new(session.SessionToken_Body))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return t.FromGRPCMessage(msg)
 }
 
 func (t *Token) MarshalJSON() ([]byte, error) {
@@ -41,13 +34,7 @@ func (t *Token) MarshalJSON() ([]byte, error) {
 }
 
 func (t *Token) UnmarshalJSON(data []byte) error {
-	msg := new(session.SessionToken)
+	return message.UnmarshalJSON(t, data, new(session.SessionToken))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return t.FromGRPCMessage(msg)
 }
 
 func (x *XHeader) MarshalJSON() ([]byte, error) {
@@ -55,13 +42,7 @@ func (x *XHeader) MarshalJSON() ([]byte, error) {
 }
 
 func (x *XHeader) UnmarshalJSON(data []byte) error {
-	msg := new(session.XHeader)
+	return message.UnmarshalJSON(x, data, new(session.XHeader))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return x.FromGRPCMessage(msg)
 }
 
 func (r *RequestMetaHeader) MarshalJSON() ([]byte, error) {
@@ -69,13 +50,7 @@ func (r *RequestMetaHeader) MarshalJSON() ([]byte, error) {
 }
 
 func (r *RequestMetaHeader) UnmarshalJSON(data []byte) error {
-	msg := new(session.RequestMetaHeader)
+	return message.UnmarshalJSON(r, data, new(session.RequestMetaHeader))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(msg)
 }
 
 func (r *RequestVerificationHeader) MarshalJSON() ([]byte, error) {
@@ -83,13 +58,7 @@ func (r *RequestVerificationHeader) MarshalJSON() ([]byte, error) {
 }
 
 func (r *RequestVerificationHeader) UnmarshalJSON(data []byte) error {
-	msg := new(session.RequestVerificationHeader)
+	return message.UnmarshalJSON(r, data, new(session.RequestVerificationHeader))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(msg)
 }
 
 func (r *ResponseMetaHeader) MarshalJSON() ([]byte, error) {
@@ -97,13 +66,7 @@ func (r *ResponseMetaHeader) MarshalJSON() ([]byte, error) {
 }
 
 func (r *ResponseMetaHeader) UnmarshalJSON(data []byte) error {
-	msg := new(session.ResponseMetaHeader)
+	return message.UnmarshalJSON(r, data, new(session.ResponseMetaHeader))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(msg)
 }
 
 func (r *ResponseVerificationHeader) MarshalJSON() ([]byte, error) {
@@ -111,13 +74,7 @@ func (r *ResponseVerificationHeader) MarshalJSON() ([]byte, error) {
 }
 
 func (r *ResponseVerificationHeader) UnmarshalJSON(data []byte) error {
-	msg := new(session.ResponseVerificationHeader)
+	return message.UnmarshalJSON(r, data, new(session.ResponseVerificationHeader))
-
-	if err := protojson.Unmarshal(data, msg); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(msg)
 }
 
 func (x *ContainerSessionContext) MarshalJSON() ([]byte, error) {

session/marshal.go

@@ -4,7 +4,6 @@ import (
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/message"
 	session "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session/grpc"
 	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/util/proto"
-	goproto "google.golang.org/protobuf/proto"
 )
 
 const (
@@ -154,12 +153,7 @@ func (x *XHeader) StableSize() (size int) {
 }
 
 func (x *XHeader) Unmarshal(data []byte) error {
-	m := new(session.XHeader)
+	return message.Unmarshal(x, data, new(session.XHeader))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return x.FromGRPCMessage(m)
 }
 
 func (l *TokenLifetime) StableMarshal(buf []byte) []byte {
@@ -193,12 +187,7 @@ func (l *TokenLifetime) StableSize() (size int) {
 }
 
 func (l *TokenLifetime) Unmarshal(data []byte) error {
-	m := new(session.SessionToken_Body_TokenLifetime)
+	return message.Unmarshal(l, data, new(session.SessionToken_Body_TokenLifetime))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return l.FromGRPCMessage(m)
 }
 
 func (c *ObjectSessionContext) StableMarshal(buf []byte) []byte {
@@ -234,12 +223,7 @@ func (c *ObjectSessionContext) StableSize() (size int) {
 }
 
 func (c *ObjectSessionContext) Unmarshal(data []byte) error {
-	m := new(session.ObjectSessionContext)
+	return message.Unmarshal(c, data, new(session.ObjectSessionContext))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return c.FromGRPCMessage(m)
 }
 
 const (
@@ -338,12 +322,7 @@ func (t *TokenBody) StableSize() (size int) {
 }
 
 func (t *TokenBody) Unmarshal(data []byte) error {
-	m := new(session.SessionToken_Body)
+	return message.Unmarshal(t, data, new(session.SessionToken_Body))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return t.FromGRPCMessage(m)
 }
 
 func (t *Token) StableMarshal(buf []byte) []byte {
@@ -375,12 +354,7 @@ func (t *Token) StableSize() (size int) {
 }
 
 func (t *Token) Unmarshal(data []byte) error {
-	m := new(session.SessionToken)
+	return message.Unmarshal(t, data, new(session.SessionToken))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return t.FromGRPCMessage(m)
 }
 
 func (r *RequestMetaHeader) StableMarshal(buf []byte) []byte {
@@ -435,12 +409,7 @@ func (r *RequestMetaHeader) StableSize() (size int) {
 }
 
 func (r *RequestMetaHeader) Unmarshal(data []byte) error {
-	m := new(session.RequestMetaHeader)
+	return message.Unmarshal(r, data, new(session.RequestMetaHeader))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(m)
 }
 
 func (r *RequestVerificationHeader) StableMarshal(buf []byte) []byte {
@@ -476,12 +445,7 @@ func (r *RequestVerificationHeader) StableSize() (size int) {
 }
 
 func (r *RequestVerificationHeader) Unmarshal(data []byte) error {
-	m := new(session.RequestVerificationHeader)
+	return message.Unmarshal(r, data, new(session.RequestVerificationHeader))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(m)
 }
 
 func (r *ResponseMetaHeader) StableMarshal(buf []byte) []byte {
@@ -532,12 +496,7 @@ func (r *ResponseMetaHeader) StableSize() (size int) {
 }
 
 func (r *ResponseMetaHeader) Unmarshal(data []byte) error {
-	m := new(session.ResponseMetaHeader)
+	return message.Unmarshal(r, data, new(session.ResponseMetaHeader))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(m)
 }
 
 func (r *ResponseVerificationHeader) StableMarshal(buf []byte) []byte {
@@ -573,10 +532,5 @@ func (r *ResponseVerificationHeader) StableSize() (size int) {
 }
 
 func (r *ResponseVerificationHeader) Unmarshal(data []byte) error {
-	m := new(session.ResponseVerificationHeader)
+	return message.Unmarshal(r, data, new(session.ResponseVerificationHeader))
-	if err := goproto.Unmarshal(data, m); err != nil {
-		return err
-	}
-
-	return r.FromGRPCMessage(m)
 }