Making a ROTMG Client + Server in Java?

As the title suggests, I've got a lot of experience in java and want to make a Realm of the Mad God private server that uses a client in java, all of the code will be public on github as I don't plan on monetizing it (Mainly plan to make this for me and my friends) and would rather people learn from what I learned, if anyone knows a good way to get some of the basic stuff going in java some help would be much appreciated.

I don't mean to judge, BUT I'm you pretty sure by now you just want to make your own bullet hell mmo

You aren't all that wrong, since most of you have a rather good knowledge of the ROTMG Packet Protocol so the best place to start asking around would be here.