detektGenerateConfig adds the configuration of plugins (#4844)

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/DetektGenerateConfigTask.kt

@@ -36,6 +36,9 @@ open class DetektGenerateConfigTask @Inject constructor(
     @get:Classpath
     val detektClasspath: ConfigurableFileCollection = project.objects.fileCollection()
 
+    @get:Classpath
+    val pluginClasspath: ConfigurableFileCollection = objects.fileCollection()
+
     @get:InputFiles
     @get:Optional
     @get:PathSensitive(PathSensitivity.RELATIVE)
@@ -70,7 +73,7 @@ open class DetektGenerateConfigTask @Inject constructor(
 
         DetektInvoker.create(task = this, isDryRun = isDryRun).invokeCli(
             arguments = arguments.get(),
-            classpath = detektClasspath,
+            classpath = detektClasspath.plus(pluginClasspath),
             taskName = name,
         )
     }

detekt-gradle-plugin/src/main/kotlin/io/gitlab/arturbosch/detekt/DetektPlugin.kt

@@ -97,6 +97,7 @@ class DetektPlugin : Plugin<Project> {
 
         project.tasks.withType(DetektGenerateConfigTask::class.java).configureEach {
             it.detektClasspath.setFrom(project.configurations.getAt(CONFIGURATION_DETEKT))
+            it.pluginClasspath.setFrom(project.configurations.getAt(CONFIGURATION_DETEKT_PLUGINS))
         }
     }