A beggar's version of weight round robin load balance -_-

## Describe the proposal
```
public class WeightRoundRobinLoadBalance implements LoadBalance {
private int totalWeight = 0;
private final List serverNodeList;

public WeightRoundRobinLoadBalance(List serverNodeList) {
this.serverNodeList = serverNodeList;
serverNodeList.forEach(p -> totalWeight += p.getWeight());
}
@Override
public ServerNode getServer() {
ServerNode result = serverNodeList.stream()
.peek(serverNode -> serverNode.addCurrent(serverNode.getWeight()))
.max(Comparator.comparingInt(ServerNode::getCurrent)).get();
result.subtractCurrent(totalWeight);
return result;
}
}
public class ServerNode {

private String ip;

private Integer weight = 1;

private Integer current = 0;

public ServerNode(String ip) {
this.ip = ip;
}

public ServerNode(String ip, Integer weight) {
this.ip = ip;
this.weight = weight;
}

public void addCurrent(int addNum){
this.current += addNum;
}
public void subtractCurrent(int addNum){
this.current -= addNum;
}
}
```

The issue includes Java implementations for WeightRoundRobinLoadBalance and ServerNode, but names no repository files, tests, or entry points. Start by locating the relevant load-balancing documentation or examples in dubbo-website, then clarify the intended scope and acceptance criteria for the weighted round-robin proposal.

Written by the indexing model from the issue text.