fix issue of multi msg cannot view on phone.

mirai-core-qqandroid/src/commonMain/kotlin/net/mamoe/mirai/qqandroid/network/protocol/packet/chat/MultiMsg.kt

@@ -48,8 +48,7 @@ internal fun Collection<ForwardMessage.INode>.calculateValidationDataForGroup(
     random: Int,
     groupCode: Long
 ): MessageValidationData {
-    val msgTransmit = MsgTransmit.PbMultiMsgTransmit(
-        msg = this.map { chain ->
+    val msgList = map { chain ->
         MsgComm.Msg(
             msgHead = MsgComm.MsgHead(
                 fromUin = chain.senderId,
@@ -75,6 +74,14 @@ internal fun Collection<ForwardMessage.INode>.calculateValidationDataForGroup(
             )
         )
     }
+    val msgTransmit = MsgTransmit.PbMultiMsgTransmit(
+        msg = msgList,
+        pbItemList = listOf(
+            MsgTransmit.PbMultiMsgItem(
+                fileName = "MultiMsg",
+                buffer = MsgTransmit.PbMultiMsgNew(msgList).toByteArray(MsgTransmit.PbMultiMsgNew.serializer())
+            )
+        )
     )
 
     val bytes = msgTransmit.toByteArray(MsgTransmit.PbMultiMsgTransmit.serializer())