public Owner getOwner() {
        final Owner copy = this.owner;
        if (copy == null) {
            throw new IllegalStateException("must try to lock at first");
        }
        return copy;
    }
Returns the 'lock-context' of current lock owner.
jraft-rheakv/rheakv-core/src/main/java/com/alipay/sofa/jraft/rhea/util/concurrent/DistributedLock.java