What means "xs @ _*" in PathList of SBT assembly-plugin?

What these phrases mean:

xs @ _*

ps @ _*

Copied from documentation:

assemblyMergeStrategy in assembly := {  case PathList("javax", "servlet", xs @ _*)         => MergeStrategy.first  case PathList(ps @ _*) if ps.last endsWith ".html" => MergeStrategy.first  case "application.conf"                            => MergeStrategy.concat  case "unwanted.txt"                                => MergeStrategy.discard  case x =>    val oldStrategy = (assemblyMergeStrategy in assembly).value    oldStrategy(x)}