java – Is Oracle JDK built from Open JDK?

Here is a ticket for Open JDK that aims to improve GC metrics. However, it is recommended that Apache Cassandra use Oracle JDK, but this improvement would be useful for monitoring metrics. If this improvement is implemented in Open JDK, can I assume that it will also be transferred to Oracle JDK?
Basically, I think I'm asking if Oracle JDK has everything from Open JDK (except for the free and free Java 11 update releases with GPL + CE license after the first six months).