Right. There's a "Java SE" (platorm spec) version, and a JDK version that corresponds to it, but not everything in the JDK affects or is dictated by the spec.

BTW, Java is developed "code first", which means that we first work on the implementation in OpenJDK, and then extract the relevant spec changes from it.

> But that is still somehow a "feature" of the Java 27 release according to Oracle.

It's a feature of the OpenJDK JDK, which is, indeed, the Java implementation done by Oracle (with contributions from others). The language is very careful, as you can see in the announcement: "JDK 27, the reference implementation of Java 27". The Java SE 27 spec is here: https://www.jcp.org/en/jsr/detail?id=402