我的问题有点像这里描述的那样。部分代码（实际上取自apache站点）如下所示

val httpHosts = new java.util.ArrayList[HttpHost]
httpHosts.add(new HttpHost("127.0.0.1", 9200, "http"))
httpHosts.add(new HttpHost("10.2.3.1", 9200, "http"))

val esSinkBuilder = new ElasticsearchSink.Builder[String](
  httpHosts,
  new ElasticsearchSinkFunction[String] {
    def createIndexRequest(element: String): IndexRequest = {
      val json = new java.util.HashMap[String, String]
      json.put("data", element)

      return Requests.indexRequest()
              .index("my-index")
              .`type`("my-type")
              .source(json)

如果我加上这三个语句，我得到的错误如下

import org.apache.flink.streaming.connectors.elasticsearch.ElasticsearchSinkFunction
import org.apache.flink.streaming.connectors.elasticsearch.RequestIndexer
import org.apache.flink.streaming.connectors.elasticsearch6.ElasticsearchSink

我犯了个错误

object elasticsearch is not a member of package org.apache.flink.streaming.connectors
object elasticsearch6 is not a member of package org.apache.flink.streaming.connectors

如果我不添加那些import语句，我会得到如下错误

Compiling 1 Scala source to E:\sar\scala\practice\readstbdata\target\scala-2.11\classes ...
[error] E:\sar\scala\practice\readstbdata\src\main\scala\example\readcsv.scala:35:25: not found: value ElasticsearchSink
[error] val esSinkBuilder = new ElasticsearchSink.Builder[String](
[error]                         ^
[error] E:\sar\scala\practice\readstbdata\src\main\scala\example\readcsv.scala:37:7: not found: type ElasticsearchSinkFunction
[error]   new ElasticsearchSinkFunction[String] {
[error]       ^
[error] two errors found
[error] (Compile / compileIncremental) Compilation failed
[error] Total time: 1 s, completed 10 Feb, 2020 2:15:04 PM

上面提到的堆栈流问题，有些函数已经扩展了。我的理解是，flink.streaming.connectors.elasticsearch必须扩展到rest库中。1） 我的理解是正确的2）如果是，我可以有完整的扩展3）如果我的理解是错误的，请给我一个解决方案。
注意：我在build.sbt中添加了以下语句

libraryDependencies += "org.elasticsearch.client" % "elasticsearch-rest-high-level-client" % "7.5.2" ,
    libraryDependencies += "org.elasticsearch" % "elasticsearch" % "7.5.2",