Update legacy protocol support to v1.21.90

legacyver/legacypacket/start_game.go

@@ -232,6 +232,8 @@ type StartGame struct {
 	WorldID string
 	// ScenarioID is always empty in vanilla and its usage is currently unknown.
 	ScenarioID string
+	// OwnerID is always empty in vanilla and its usage is currently unknown.
+	OwnerID string
 	// UseBlockNetworkIDHashes is true if the client should use the hash of a block's name as its network ID rather than
 	// its index in the expected block palette. This is useful for servers that wish to support multiple protocol versions
 	// and custom blocks, but it will result in extra bytes being written for every block in a sub chunk palette.
@@ -309,6 +311,9 @@ func (pk *StartGame) Marshal(io protocol.IO) {
 		io.String(&pk.ServerID)
 		io.String(&pk.WorldID)
 		io.String(&pk.ScenarioID)
+		if proto.IsProtoGTE(io, proto.ID818) {
+			io.String(&pk.OwnerID)
+		}
 	}
 	io.String(&pk.LevelID)
 	io.String(&pk.WorldName)