OpenJDK is the original version of Java with a few features stripped out, not a reimplementation.
See the History section of https://en.wikipedia.org/wiki/OpenJDK?wprov=sfla1
Thank you for the link. I stand corrected and better learned.
See the History section of https://en.wikipedia.org/wiki/OpenJDK?wprov=sfla1
Disclaimer : I'm still new and learning Java.