The method `java.lang.ThreadGroup.stop()` has been removed in this release. This inherently unsafe method was deprecated in JDK 1.2 (1998), deprecated for removal in Java 18, and re-specified/degraded in Java 20 to throw `UnsupportedOperationException` unconditionally. Code that uses this method will no longer compile. Code using this method that is compiled to older releases will now throw `NoSuchMethodError` instead of `UnsupportedOperationException` if executed on JDK 23 or newer.