manually specify shadowjar task on shaded addons

buildSrc/src/main/kotlin/AddonConfig.kt

@@ -1,3 +1,4 @@
+import com.github.jengelman.gradle.plugins.shadow.tasks.ShadowJar
 import java.io.File
 import java.util.function.Predicate
 import org.gradle.api.Project
@@ -20,7 +21,11 @@ fun Project.addonDir(dir: File, task: Task) {
             it.delete()
         }
         forSubProjects(":common:addons") {
-            val jar = (tasks.named("jar").get() as Jar)
+            val jar = if(tasks.findByName("shadowJar") != null) {
+                (tasks.named("shadowJar").get() as ShadowJar)
+            } else {
+                (tasks.named("jar").get() as Jar)
+            }
             
             val boot = if (extra.has("bootstrap") && extra.get("bootstrap") as Boolean) "bootstrap/" else ""
             val target = File(dir, boot + jar.archiveFileName.get())