I must admit to not following recent XMR development much the last couple years and last recall after Maxwell wrote bulletproofs that it was intended to be implemented. I did check and see that it had been re-written and implemented by another in a different custom-tailored way. I do pay the XMR guys respect for doing their thing and branching their way. No disrespect, I should have generally said that the Bitcoin core devs have paved work for them. No, I did not mean core devs are writing all XMR code.

https://eprint.iacr.org/2017/1066.pdf