package api.svc;

option go_package = "api/svc";

  rpc GetTrieNode(api.infra.GetTrieNodeReq) returns (api.infra.KVNode) {
    option (google.api.http) = {
      post: "/trie/node:get"
      body: "*"
      additional_bindings {
        get: "/trie/node/{id}"
      }
      additional_bindings {
        get: "/trie/node/path/{path}"
      }
    };
  }

package api.infra;

option go_package = "api/infra";

message GetTrieNodeReq {
  oneof x {
    string id   = 1;
    string path = 2;
  }
}

	if protoReq.X == nil {
		protoReq.X = &GetTrieNodeReq_Id{}
	} else if _, ok := protoReq.X.(*GetTrieNodeReq_Id); !ok {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "expect type: *GetTrieNodeReq_Id, but: %t\n", protoReq.X)
	}
	protoReq.X.(*GetTrieNodeReq_Id).Id, err = runtime.String(val)
	if err != nil {
		return nil, metadata, status.Errorf(codes.InvalidArgument, "type mismatch, parameter: %s, error: %v", "id", err)
	}

./protoc-gen-grpc-gateway -version
Version 2.3.0, commit bcc34ef50bda81faae5d4bbfca2e7ea8fe4700c8, built at 2021-02-25T18:32:39Z