What coffee does McDonald's use?

I'm curious, can you tell me what brand of coffee does McDonald's use to brew their signature beverages? Are they known to have a partnership with a specific coffee roaster, or do they source their beans from multiple suppliers? And, do the coffee options vary by region or country, or is there a consistent taste and quality that customers can expect no matter where they are in the world? I'm genuinely interested in knowing more about the coffee that powers the iconic coffee drinks served at McDonald's.