Issue: code generate for nested group broken

` syntax = "proto2"; package pbdata;

message ValueType { optional int32 int_type =1; optional int64 long_type = 2; optional float float_type = 3; optional string string_type =4; }

message Log { required int64 log_timestamp =1; optional string ip = 2; optional group Field = 3 { repeated group Map = 1 { required string key = 1; optional ValueType value = 2; } } } `