public void removeListener(IoFutureListener listener) {
        if (listener == null) {
            return;
        }
        synchronized (lock) {
            if (this.listeners != null) {
                this.listeners.remove(listener);
            }
        }
    }
A lock used by the wait() method
lts-core/src/main/java/com/github/ltsopensource/nio/handler/IoFuture.java