scala代码编译不通过

package com.imooc.scala.stream.checkpoint

import org.apache.flink.api.common.restartstrategy.RestartStrategies
import org.apache.flink.streaming.api.scala.StreamExecutionEnvironment
import org.apache.flink.streaming.api.windowing.time.Time

import java.util.concurrent.TimeUnit


object CheckpointApp {
  def main(args: Array[String]): Unit = {
    val env = StreamExecutionEnvironment.getExecutionEnvironment

    //开启checkpoint 默认exactly once
    env.enableCheckpointing(5000);
    env.setRestartStrategy(RestartStrategies.fixedDelayRestart(  //这一行编译不通过
      3, // number of restart attempts
      Time.of(10, TimeUnit.SECONDS) // delay
    ))

    val text = env.socketTextStream("localhost", 9999)
    text.print().setParallelism(1)
    env.execute("CheckpointApp")
  }
}

请问老师是什么原因？