public Object invokeSync(final Connection conn, final Object request, final int timeoutMillis)
                                                                                                  throws RemotingException,
                                                                                                  InterruptedException {
        ensureStarted();
        return this.rpcRemoting.invokeSync(conn, request, null, timeoutMillis);
    }
Synchronous invocation using a {@link Connection} <br>
<p>
Notice:<br>
  <b>DO NOT modify the request object concurrently when this method is called.</b>

@param conn connection
@param request request
@param timeoutMillis timeoutMillis
@return Object
@throws RemotingException remoting exception remoting exception
@throws InterruptedException interrupted exception
src/main/java/com/alipay/remoting/rpc/RpcServer.java