It appears that somewhere in the process of JDK-8370227 the most recent change to the micros-javac got removed, this diff needs to be reapplied to exclude jdk.jsobject:


                     final String ename = entry.getName();
- if (!ename.startsWith("java.desktop") && !ename.startsWith("jdk.internal.vm.compiler") && !ename.startsWith("jdk.aot") && !ename.startsWith("jdk.accessibility")) {
+ if (!ename.startsWith("java.desktop") && !ename.startsWith("jdk.internal.vm.compiler") && !ename.startsWith("jdk.aot") && !ename.startsWith("jdk.accessibility") && !ename.startsWith("jdk.jsobject")) {
                         if (!entry.isDirectory() && ename.endsWith(".java")) {
                             Path dst = root.resolve(ename);