Specify metadata in jar task (likely used by Jib)

buildSrc/src/main/kotlin/twomartens.spring-boot.gradle.kts

@@ -62,7 +62,7 @@ tasks.named("buildAll") {
 
 val formatter: DateTimeFormatter = ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSZ")
 
-tasks.bootJar {
+tasks.jar {
     manifest {
         attributes["Implementation-Title"] = rootProject.name
         attributes["Implementation-Version"] = archiveVersion.get()

module-server/src/main/kotlin/de/twomartens/wahlrecht/controller/VersionHtmlController.kt

@@ -32,14 +32,16 @@ class VersionHtmlController {
     }
 
     private fun getTitle(): String {
-        val title = VersionHtmlController::class.java.getPackage().implementationTitle
+        val title = VersionHtmlController::class.java.`package`.implementationTitle
+                ?: return "application"
         return title.ifBlank {
             "application"
         }
     }
 
     private fun getVersion(): String {
-        val version = VersionHtmlController::class.java.getPackage().implementationVersion
+        val version = VersionHtmlController::class.java.`package`.implementationVersion
+                ?: return "DEVELOPER"
         return version.ifBlank {
             "DEVELOPER"
         }