@Override
    public long getLastAppliedLogIndex() {
        this.readLock.lock();
        try {
            if (this.state.isActive()) {
                return this.fsmCaller.getLastAppliedIndex();
            }
            throw new IllegalStateException("The node is not active, current state: " + this.state);
        } finally {
            this.readLock.unlock();
        }
    }
Retrieve current configuration this node seen so far. It's not a reliable way to
retrieve cluster peers info, you should use {@link #listPeers()} instead.

@return current configuration.

@since 1.0.3
jraft-core/src/main/java/com/alipay/sofa/jraft/core/NodeImpl.java