Syntax error when parsing complicated service rpc option

[liiri]

My proto file:

syntax = "proto3";

package my.proto.v1;

import "google/api/annotations.proto";
import ...

service MyService {
    rpc Create (MyRequest) returns (MyResponse) {
        option (google.api.http).get = "/api/my";
        option (my.custom.option) = {
          value1: "A"
          value2: "B"
        };
    }
}

message MyRequest {
}

message MyResponse {
}

I'm getting syntax error on the custom option:

  message: `Expected "'", ".", "/*", "//", "0", "\\"", "false", "inf", "nan", "true", [ \\r\\n\\t], [0-9], [1-9], [A-Za-z], or [\\-+] but "{" found.`,

[liiri]

Also reproduced for less custom option, it seems to be with using an object under option

         option (google.api.http) = {
           patch: "/v1/messages/{message_id}"
           body: "message"
         };