Not Able to specify timestamp with the message

Hi,
I am using @log4js-node/gelf@1.0.2. I am sending a message with timestamp info, which is not being picked up by the module.

const log4js = require('log4js');

log4js.configure({
  appenders: {
    gelf: { type: '@log4js-node/gelf', host: 'localhost', port: '12201', }
  },
  categories: {
    default: { appenders: ['gelf'], level: 'info'  }
  }
});

module.exports = log4js;

const logger = log4js.getLogger();

logger.info({ GELF: true, _tool: 'proxy-parser', _uniqueId: 'test', _timestamp: 1611283489  }, 'very very old message');

But the message is getting logged with the current timestamp on graylog.

Looks like the issue with this line

gelf/lib/index.js

Line 95 in 4786403

    
           msg.timestamp = msg.timestamp || new Date().getTime() / 1000; // log should use millisecond

It should have been

msg.timestamp = msg._timestamp || new Date().getTime() / 1000; // log should use millisecond

Can this be fixed?

Thank You,
Phani