looking for a solution missing main class

Dockerfile

 FROM amd64/adoptopenjdk:11-jre
+#FROM openjdk:8-jre-alpine
 ADD target/scala-2.13/app.jar /app/app.jar
 CMD java -jar /app/app.jar

build.sbt

@@ -16,22 +16,22 @@ lazy val root = (project in file("."))
     mainClass in assembly := Some("ch.memobase.Main"),
     test in assembly := {},
     assemblyMergeStrategy in assembly := {
-      case "log4j.properties" => MergeStrategy.first
-      case "module-info.class" => MergeStrategy.discard
-      case "log4j2.xml" => MergeStrategy.first
+      //case "log4j.properties" => MergeStrategy.first
+      //case "module-info.class" => MergeStrategy.discard
+      //case "log4j2.xml" => MergeStrategy.first
       case "META-INF/MANIFEST.MF" => MergeStrategy.discard
-      case _  => MergeStrategy.last
+      //case _  => MergeStrategy.last
 
     },
-    assemblyExcludedJars in assembly := {
-      val cp = (fullClasspath in assembly).value
-      cp filter {_.data.getName == "httpclient-osgi-4.5.12.jar"}
-    },
+    //assemblyExcludedJars in assembly := {
+    //  val cp = (fullClasspath in assembly).value
+    //  cp filter {_.data.getName == "httpclient-osgi-4.5.12.jar"}
+    //},
     resolvers ++= Seq(
       "Memobase Utils" at "https://dl.bintray.com/memoriav/memobase"
     ),
     libraryDependencies ++= Seq(
-      iiifApis,
+      //iiifApis,
       // iiifPresentationApi,
       kafkaStreams,
       log4jApi,
@@ -53,3 +53,5 @@ lazy val root = (project in file("."))
 
     )
   )
+
+logLevel := Level.Debug
\ No newline at end of file

src/main/scala/ch/memobase/edm/Extractors.scala

@@ -18,7 +18,6 @@
 
 package ch.memobase.edm
 
-import org.dmfs.jems.predicate.elementary.Nothing
 import ujson.Value.{Value => JValue}
 import ujson.{Arr => JArr, Obj => JObj, Str => JStr}