Access to jdk.internal.io.JdkConsoleImpl.restoreEcho in this runnable should be guarded by readLock:
 
            // Add a shutdown hook to restore console's echo state should
            // it be necessary.
            SharedSecrets.getJavaLangAccess()
                    .registerShutdownHook(0 /* shutdown hook invocation order */,
                            false /* only register if shutdown is not in progress */,
                            new Runnable() {
                                public void run() {
                                    try {
                                        if (restoreEcho) {
                                            echo(true);
                                        }
                                    } catch (IOException x) { }
                                }
                            });