These source files were generated via MCP, for your usage. I've set up this old MCP940 for 1.12 to work with 1.12.2. I zipped and committed the decompiled source files if you want to view them.
If you don't want to setup Port Forwarding, you can use TCP tunnelling instead: Make sure you have "server-ip=localhost" in your server.properties file Run install_node.bat to install NodeJS and ...