Scala:"sbt assembly"でMerging エラーが発生した場合の対処法（sbt 1.0以降）

環境

• Windows10
• java version 1.8.0_171
• scala 2.12.3
• sbt 1.1.6

project\assembly.sbt

addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.7")

project\plugins.sbt

resolvers += Resolver.url("artifactory", url("http://scalasbt.artifactoryonline.com/scalasbt/sbt-plugin-releases"))(Resolver.ivyStylePatterns)
addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "0.14.7")

javax.mail　を組み込むときにはまった。

    "javax.mail" % "javax.mail-api" % "1.5.1",
    "javax.mail" % "mail" % "1.5.0-b01",

sbt assembly で Merging エラー

 sbt assembly
　↓
[warn] Merging 'META-INF\NOTICE' with strategy 'rename'

対処法（build.sbtに以下を追記）

build.sbt

assemblyMergeStrategy in assembly := {
  case PathList("javax", "servlet", xs @ _*)         => MergeStrategy.first
  case PathList(ps @ _*) if ps.last endsWith ".html" => MergeStrategy.first
  case PathList(ps @ _*) if ps.last endsWith ".properties" => MergeStrategy.first
  case PathList(ps @ _*) if ps.last endsWith ".xml" => MergeStrategy.first
  case PathList(ps @ _*) if ps.last endsWith ".types" => MergeStrategy.first
  case PathList(ps @ _*) if ps.last endsWith ".class" => MergeStrategy.first
  case "application.conf"                            => MergeStrategy.concat
  case "unwanted.txt"                                =>
MergeStrategy.discard
  case PathList("META-INF", "MANIFEST.MF") => MergeStrategy.discard
  case PathList("META-INF", "mailcap.default") => MergeStrategy.discard
  case PathList("META-INF", "mimetypes.default") => MergeStrategy.discard
 case x =>
    val oldStrategy = (assemblyMergeStrategy in assembly).value
    oldStrategy(x)
}

補足

sbt0.13以前だと

build.sbt

mergeStrategy in assembly <<= (mergeStrategy in assembly) { (old) =>
  {
    case "META-INF/MANIFEST.MF" => MergeStrategy.discard
    case x => MergeStrategy.first
  }
}

で対処できた。

ちなみにsbtのバージョンは

sbt about

で確認できる。