Introduce validation against source

modules/forgefed/star.go

@@ -4,6 +4,8 @@
 package forgefed
 
 import (
+	"fmt"
+
 	ap "github.com/go-ap/activitypub"
 	"github.com/valyala/fastjson"
 )
@@ -42,6 +44,16 @@ func StarNew(id ap.ID, ob ap.ID) *Star { // ToDo: May be used later in creating
 	return &o
 }
 
+func (a Star) ValidateStar() error {
+
+	if a.Source != "forgejo" {
+		return fmt.Errorf("currently, only a forgejo source is supported")
+	}
+
+	return nil
+
+}
+
 func (a Star) MarshalJSON() ([]byte, error) {
 	b := make([]byte, 0)
 	ap.JSONWrite(&b, '{')