A message type's toObject function includes extra underscore-prefixed fields when the oneofs option is set

[murgatroid99]

protobuf.js version: 7.4.0

Reproduction example:

Proto message:

syntax = "proto3";

message Test {
  optional string field = 1;
}

Code (node.js):

const protobufjs = require('protobufjs');
const root = protobufjs.loadSync('./test.proto');
console.log(root.Test.toObject({field: 'hello'}, {oneofs: true}));

Expected output:

{field: 'hello'}

Actual output:

{ field: 'hello', _field: 'field' }