I have seen Where to find Java 6 JSSE/JCE Source Code? and asked the question myself How to get JRE/JDK with matching source? but I don\'t either of these was specific enough
Following up on this, you can download OpenJDK:
https://adoptopenjdk.net/
and match it up exactly to the source code from
https://github.com/AdoptOpenJDK/openjdk-jdk8u
Currently u172-b11 is the latest version, but they are in sync and will work on all platforms.