Can start here, https://dev.java/contribute/openjdk/

"Once you have contributed several changes (usually two) you can become an Author. An author has the right to create patches but cannot push them. To push a patch, you need a Sponsor. Gaining a sponsorship is usually achieved through the discussions you had on the mailing lists.

In order to become an Author, you also need to sign the Oracle Contribution Agreement (OCA)."

The go into https://openjdk.org/bylaws

"The OpenJDK Lead is an OpenJDK Member, appointed by Oracle, who directs the major efforts of the Community, which are new implementations of the Java SE Platform known as JDK Release Projects."

And this nice contribution overview from Java 22,

https://blogs.oracle.com/java/post/the-arrival-of-java-22

"Of the 26,447 JIRA issues marked as fixed in Java 11 through Java 22 at the time of their GA, 18,842 were completed by Oracle employees while 7,605 were contributed by individual developers and developers working for other organizations. Going through the issues and collating the organization data from assignees results in the following chart of organizations sponsoring the development of contributions in Java:"

To spare you the math, 77% were done by Oracle employees.

Now please show us how Kotlin compiles for Android without using Java.

Doesn't look like Google got rid of Oracle to me, more like they didn't even considered Dart, nor Go could stand a chance against the Java ecosystem among Android developers.