Scala assemblyMergeStrategy类型错误

我正在尝试建立一个小项目，用scala编写aws lambda：

javacOptions ++= Seq("-source", "1.8", "-target", "1.8", "-Xlint")

lazy val root = (project in file(".")).
  settings(
    name := "xxx",
    version := "0.1",
    scalaVersion := "2.12.3",
    retrieveManaged := true
  )

libraryDependencies ++= Seq(
  "com.amazonaws" % "aws-lambda-java-core"   % "1.1.0" % Provided,
  "com.amazonaws" % "aws-lambda-java-events" % "1.1.0" % Provided,
  "org.scalatest" % "scalatest" % "2.2.6" % Test
)

scalacOptions += "-deprecation"

assemblyMergeStrategy in assembly <<= (assemblyMergeStrategy in assembly) {
  (old) => {
    case PathList("META-INF", xs @ _*) => MergeStrategy.discard
    case x => MergeStrategy.first
  }
}

javacOptions++=Seq（“-source”、“1.8”、“-target”、“1.8”、“-Xlint”）
lazy val root=（文件中的项目（“.”）。
背景(
名称：=“xxx”，
版本：=“0.1”，
scalaVersion:=“2.12.3”，
retrieveManaged:=true
)
libraryDependencies++=Seq(
“com.amazonaws”%”aws lambda java core“%”1.1.0“%提供，
提供了“com.amazonaws”%”aws lambda java事件“%”1.1.0”%、，
“org.scalatest”%“scalatest”%“2.2.6”%Test
)
ScalaOptions+=“-弃用”
assembly MergeStrategy.discard中的assembly MergeStrategy
案例x=>MergeStrategy.first
}
}

结果：

xxx/build.sbt:25:错误：未找到：值

---

assembly中的assemblyMergeStrategy您是否在项目/plugins.sbt文件中引用了assembly插件？ assemblyMergeStrategy由插件定义

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.3")

---

在较新版本中，可以将其放在project/assembly.sbt中。有关最新信息，请参阅。