How to connect to the Unreal Engine client?

[jsonhet]

How to connect to the Unreal Engine client?
After creating the server according to the document, I tried to connect to the server on the Unreal Engine client but kept getting an error message: Response code was not 101

Additional context
Core code：
`
import org.java_websocket.WebSocket;
import org.java_websocket.drafts.Draft;
import org.java_websocket.exceptions.InvalidDataException;
import org.java_websocket.framing.CloseFrame;
import org.java_websocket.framing.Framedata;
import org.java_websocket.handshake.ClientHandshake;
import org.java_websocket.handshake.ServerHandshakeBuilder;
import org.java_websocket.server.WebSocketServer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.InetSocketAddress;
import java.net.UnknownHostException;

public class SourceSocket extends WebSocketServer {

private Logger logger = LoggerFactory.getLogger(SourceSocket.class);

private SourceMessage sourceMessage;

public SourceSocket(InetSocketAddress address) {
    super(address);
}

public SourceSocket(int port) throws UnknownHostException {
    super(new InetSocketAddress(port));
    sourceMessage = SourceMessage.getInstance();
}

@Override
public ServerHandshakeBuilder onWebsocketHandshakeReceivedAsServer(WebSocket conn, Draft draft, ClientHandshake request) throws InvalidDataException {
    ServerHandshakeBuilder builder = super.onWebsocketHandshakeReceivedAsServer(conn, draft, request);
    if (!StringUtils.isConformResourceDescriptorRule(request.getResourceDescriptor())){
        throw new InvalidDataException(CloseFrame.POLICY_VALIDATION, "您的链接格式不符合！");
    }
    return builder;
}

`