Javalin .mjs MIME type

This project reproduces an issue I've discovered with Javalin returning no Content-Type header for .mjs files.

Instructions

• mvn exec:java
• curl -I -X GET http://localhost:7070/test.js
  • Observe header: Content-Type: application/javascript
• curl -I -X GET http://localhost:7070/test.mjs
  • Observe no Content-Type header

Expected behaviour: .mjs should have Content-Type: application/javascript header