What the heck is this compiler? Can anyone decompile this .class?

A person i know was recently grabbed by this fake minecraft texture pack (i know, dumb, idk how you fall for it). I want to see where the credentials go etc. (Probably a discord webhook). Can anyone help me with this? I dont have alot of experience with java so if its a common one or not (im also wrong on alot of things im saying probably but pls dont flame me)