coffee does not dehydrate

edit: here are some sources that look serious if you're interested but there's plenty of evidence. I'm an endurance athlete (so I'm mindful about dehydration) and I enjoy coffee a lot so I researched this a bit.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3886980/

https://www.ncbi.nlm.nih.gov/pubmed/17620932