(minor) Improve readability of pluginMarkers.gradle, fix indent in file

(minor) Clarify the comment on the setUpSeparateArtifact block

libraries/tools/gradle-tools/pluginMarkers.gradle

@@ -11,6 +11,7 @@ ext.pluginMarkerProject = { String pluginProjectId ->
         compile pluginProject
     }
 
+    // Remove the default JAR artifact added by the Java plugin
     configurations.archives.artifacts.clear()
 
     configurePublishing(project)
@@ -19,7 +20,7 @@ ext.pluginMarkerProject = { String pluginProjectId ->
 
     version = project.version + (findProperty('marker_version_suffix') ?: "")
 
-    for (pluginId in pluginProject.pluginBundle.plugins*.id) {
+    for (pluginId in pluginProject.pluginBundle.plugins.collect { it.id }) {
         def artifactName = "${pluginId}.gradle.plugin"
 
         artifacts {
@@ -27,11 +28,12 @@ ext.pluginMarkerProject = { String pluginProjectId ->
                 archives(emptyJar) {
                     group = pluginId
                     name = artifactName
-                    classifier theClassifier
+                    classifier = theClassifier
                 }
             }
         }
 
+        // Publish each gradle plugin marker under its own Maven coordinates pluginId:pluginId.gradle.plugin
         def setUpSeparateArtifact = {
             addFilter(pluginId) { artifact, file -> artifact.name == artifactName }
             def pom = pom(pluginId)

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/resources/testProject/pluginsDsl/allopenPluginsDsl/settings.gradle

@@ -1,6 +1,6 @@
 pluginManagement {
     repositories {
-         maven { url '<mavenLocalUrl>' }
+        maven { url '<mavenLocalUrl>' }
         gradlePluginPortal()
     }
 }