1.12 forge mdk crashes on run

[roadturtle]

whenever i try to runClient for a mod i’m making in eclipse i keep getting and error saying that byteBuffer.flip() is not a function. Ive been looking everywhere to find an answer but couldn’t find one that helped me, does anyone have a way to fix this? yes i’m 99% sure i’m using java 8 and not java 9 or above.