[Go] When define Enum in/not_in in Map, compiler error: undeclared name: _PagingRequest_OrderBy_InLookup

[yrcs]

enum Order {
   	// ascending order
   	ASC = 0;
   	// descending order
   	DESC = 1;
}

message PagingRequest {
​    	map<string, Order> orderBy = 4 [(validate.rules).map = {ignore_empty: true, keys: {string: {min_len: 1}}, values: {enum: {defined_only: true, in:[0, 1]}}}]; 
}