WooCommerce Postback fails due to Java issue?

Unless I'm mistaken, no version of Java includes trust for LE today, although I understand it's being pursued for future versions of Java.

Do not despair, however: Trust for LE can be added to the system truststores without upgrading Java, if you can do that or persuade someone. Failing that, it can be added in the Java code itself. I recall seeing descriptions of how to do both somewhere in these forums.