java – is Oracle JDK built from Open JDK?

There is this ticket here for Open JDK which aims to improve GC metrics. However, Apache Cassandra is recommended to use Oracle JDK, but this enhancement would be useful for monitoring metrics. If this enhancement is implemented in Open JDK, can I assume that it will also be ported to Oracle JDK?
Basically, I think I ask if the Oracle JDK has all that it has for Open JDK (with the exception of free and free upgrades of Java 11 under GPL + CE after the first six months)?