Use https://github.com/sbt/sbt-assembly?tab=readme-ov-file#merge-stra…

…tegy merge strategy

build.sbt

@@ -51,46 +51,7 @@ val commonSettings: immutable.Seq[Def.Setting[_]] = List(
   ),
   ThisBuild / assemblyMergeStrategy := {
     case "META-INF/MANIFEST.MF" => MergeStrategy.discard
-    case PathList(ps @ _*) if ps.last equalsIgnoreCase "Log4j2Plugins.dat" =>
-      import java.io.FileInputStream
-      import java.io.FileOutputStream
-      import org.apache.logging.log4j.core.config.plugins.processor.PluginCache
-
-      import scala.collection.JavaConverters.asJavaEnumerationConverter
-
-      import sbt.io.{IO, Using}
-      import sbtassembly.Assembly.Dependency
-
-      CustomMergeStrategy("Log4j2Plugins") { conflicts =>
-        val dependencyStreamResource =
-          Using.resource((dependency: Dependency) => dependency.stream())
-        val tempDir = "target/log4j2-plugin-cache"
-        val urls = conflicts
-          .map { conflict =>
-            dependencyStreamResource(conflict) { is =>
-              val file = new File(
-                s"$tempDir/${conflict.module.get.jarName}-Log4j2Plugins.dat"
-              )
-              IO.write(file, IO.readBytes(is))
-              file.toURI.toURL
-            }
-          }
-        val aggregator = new PluginCache()
-        aggregator.loadCacheFiles(urls.toIterator.asJavaEnumeration)
-        val pluginCache = new File(s"$tempDir/Log4j2Plugins.dat")
-        val pluginCacheOutputStream = new FileOutputStream(pluginCache)
-        aggregator.writeCache(pluginCacheOutputStream)
-        pluginCacheOutputStream.close()
-        Right(
-          Vector(
-            JarEntry(
-              conflicts.head.target,
-              () => new FileInputStream(pluginCache)
-            )
-          )
-        )
-      }
-
+    case PathList(ps @ _*) if ps.last equalsIgnoreCase "Log4j2Plugins.dat" => sbtassembly.Log4j2MergeStrategy.plugincache
     case _ => MergeStrategy.first
   },
   dependencyOverrides ++= Seq(

project/plugins.sbt

@@ -1,5 +1,7 @@
 addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.1.5")
 
+addSbtPlugin("com.michaelpollmeier" % "sbt-assembly-log4j2" % "1.1.3")
+
 addSbtPlugin("com.gu" % "sbt-riffraff-artifact" % "1.1.18")
 
 addDependencyTreePlugin