capture and split notification if it has multiple hosts

pkg/actor/grain_pool.go

@@ -2,6 +2,7 @@ package actor
 
 import (
 	"context"
+	"io"
 	"net/http"
 
 	"google.golang.org/protobuf/proto"
@@ -34,7 +35,7 @@ type Host interface {
 	AnnounceExpiry(ids []uint64)
 	Negotiate(otherHosts []string) ([]string, error)
 	Name() string
-	Proxy(id uint64, w http.ResponseWriter, r *http.Request) (bool, error)
+	Proxy(id uint64, w http.ResponseWriter, r *http.Request, customBody io.Reader) (bool, error)
 	Apply(ctx context.Context, id uint64, mutation ...proto.Message) (bool, error)
 	GetActorIds() []uint64
 	Close() error