property IncomingMessage.prototype.headersDistinct
Similar to message.headers, but there is no join logic and the values are
always arrays of strings, even for headers received just once.
// Prints something like:
//
// { 'user-agent': ['curl/7.22.0'],
// host: ['127.0.0.1:8000'],
// accept: ['*'] }
console.log(request.headersDistinct);
Dict<string[]>