docs: public static Subject getSubject() {
        if (SUBJECT.get() != null) {
           return SUBJECT.get().peek();
        } else {
           AccessControlContext acc = AccessController.getContext();
           if (System.getSecurityManager() == null) {
              return Subject.getSubject(acc);
           } else {
              return AccessController.doPrivileged((PrivilegedAction<Subject>) () -> Subject.getSubject(acc));
           }
        }
     }