clustering example fails with assembly sbt command

[bwbecker]

I pulled the cluster example project from https://developer.lightbend.com/start/?group=akka&project=akka-samples-cluster-scala

With no other changes, I did sbt assembly to get a fat jar file to run without all the scala infrastructure. It gave

[error] 1 error was encountered during merge
[error] stack trace is suppressed; run last assembly for the full output
[error] (assembly) deduplicate: different file contents found in the following:
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-core/2.11.4/jackson-core-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-annotations/2.11.4/jackson-annotations-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/core/jackson-databind/2.11.4/jackson-databind-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/datatype/jackson-datatype-jdk8/2.11.4/jackson-datatype-jdk8-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/datatype/jackson-datatype-jsr310/2.11.4/jackson-datatype-jsr310-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/module/jackson-module-parameter-names/2.11.4/jackson-module-parameter-names-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/dataformat/jackson-dataformat-cbor/2.11.4/jackson-dataformat-cbor-2.11.4.jar:module-info.class
[error] /Users/bwbecker/Library/Caches/Coursier/v1/https/repo1.maven.org/maven2/com/fasterxml/jackson/module/jackson-module-paranamer/2.11.4/jackson-module-paranamer-2.11.4.jar:module-info.class
[error] Total time: 6 s, completed Aug. 9, 2022, 10:39:48 a.m.

Adding the following to the build.sbt file fixed the issue:

    // See https://stackoverflow.com/questions/64858397/sbt-assembly-deduplicate-different-file-contents-found-in-the-following-jackso/73293137#73293137
    assembly / assemblyMergeStrategy := {
      case "module-info.class" => MergeStrategy.discard
      case x =>
        val oldStrategy = (assembly / assemblyMergeStrategy).value
        oldStrategy(x)
    }

[bwbecker]

In preparing a pull request, I discovered that the above does not work. It generates the jar file but when trying to run it, java complains that the manifest is missing. Tried to fix with

//case PathList("META-INF", "MANIFEST.MF") => MergeStrategy.concat

but that gave another duplicate error.

I don't know how to resolve it.