Why do I keep getting a request to install JDK on mid 2015 MacBook Pro
You may need to download legacy Java that apple doesn't automatically ship anymore. That said, if you think you know which application may be what's requiring this, it may be a good idea to get rid of it if you don't need it. If you do need it, this should be the right download: https://support.apple.com/kb/dl1572?locale=en_US