They have been rewamping the Java standard library slowly and silently over the last couple of years in anticipation for Loom. With Java 14 they re-wrote the tcp socket class. In Java 15 they're re-implementing the udp socket class. These re-implementations are being done to support loom seamlessly in a future update.

They also collaborated with IntelliJ to find bugs related to debugging Java apps, to make sure Loom doesn't break anything there.

Loom is well underway. I wouldn't be surprised if we saw Loom in Java 19 or 20. So in 2-3 years.