fix sbt-assembly

.github/workflows/ci.yml

@@ -32,3 +32,7 @@ jobs:
         shell: bash
         run: |
           sbt +test
+      - name: Verify assembly
+        shell: bash
+        run: |
+          sbt +package +assembly

build.sbt

@@ -38,6 +38,13 @@ lazy val `spot-complete` = project
         assembly / assemblyJarName := s"${name.value}_${scalaBinaryVersion.value}-${version.value}.jar",
         assembly / assemblyOption ~= {
             _.withIncludeScala(false)
+        },
+        assembly / assemblyMergeStrategy := {
+            // TODO this okio business may well be wrong. Revisit this once we have an integration test to run.
+            case "META-INF/okio.kotlin_module" => MergeStrategy.first
+            case x =>
+                val oldStrategy = (ThisBuild / assemblyMergeStrategy).value
+                oldStrategy(x)
         }
     )
 

project/Dependencies.scala

@@ -6,7 +6,12 @@ object Dependencies {
   val `opentelemetry-api` = "io.opentelemetry" % "opentelemetry-api" % openTelemetryVersion
   val `opentelemetry-sdk` = "io.opentelemetry" % "opentelemetry-sdk" % openTelemetryVersion
   val `opentelemetry-sdk-autoconfigure` = "io.opentelemetry" % "opentelemetry-sdk-extension-autoconfigure" % openTelemetryVersion
-  val `opentelemetry-exporter-otlp` = "io.opentelemetry" % "opentelemetry-exporter-otlp" % openTelemetryVersion
+  val `opentelemetry-exporter-otlp` = "io.opentelemetry" % "opentelemetry-exporter-otlp" % openTelemetryVersion excludeAll(
+    // Okio includes three JVM-versions of kotlin-stdlib. This causes problems for sbt-assembly-plugin. Here we assume
+    // that by now everyone is running Spark on JDK 11, and we omit JDK 8.
+    ExclusionRule("org.jetbrains.kotlin", "kotlin-stdlib-jdk7"),
+    ExclusionRule("org.jetbrains.kotlin", "kotlin-stdlib-jdk8")
+  )
   val `spark-core` = "org.apache.spark" %% "spark-core" % "3.5.1"
   val scalactic = "org.scalactic" %% "scalactic" % "3.2.19"
   val scalaTest = "org.scalatest" %% "scalatest" % "3.2.19"