Fixes for new MPP publishing

* Generate the JARs with the same names as they are published.
  Put the target name in the JAR name's appendix instead of classifier.

* Configure Maven publications eagerly to allow their editing by user.

* Take KotlinVariant's coordinates from the MavenPublication.
  If the user changes Maven coordinates of the publication, this ensures
  the parent component to have the updated information.

libraries/tools/kotlin-gradle-plugin-integration-tests/src/test/kotlin/org/jetbrains/kotlin/gradle/NewMultiplatformIT.kt

@@ -46,9 +46,9 @@ class NewMultiplatformIT : BaseGradleIT() {
                 assertTasksExecuted(*compileTasksNames.toTypedArray(), ":jvm6Jar", ":nodeJsJar", ":metadataJar")
 
                 val groupDir = projectDir.resolve("repo/com/example")
-                val jvmJarName = "sample-lib-jvm6/1.0/sample-lib-jvm6-1.0-jvm6.jar"
-                val jsJarName = "sample-lib-nodejs/1.0/sample-lib-nodejs-1.0-nodeJs.jar"
-                val metadataJarName = "sample-lib-metadata/1.0/sample-lib-metadata-1.0-metadata.jar"
+                val jvmJarName = "sample-lib-jvm6/1.0/sample-lib-jvm6-1.0.jar"
+                val jsJarName = "sample-lib-nodejs/1.0/sample-lib-nodejs-1.0.jar"
+                val metadataJarName = "sample-lib-metadata/1.0/sample-lib-metadata-1.0.jar"
                 val wasmKlibName = "sample-lib-wasm32/1.0/sample-lib-wasm32-1.0.klib"
                 val nativeKlibName = "sample-lib-$hostTargetName/1.0/sample-lib-$hostTargetName-1.0.klib"
 
@@ -383,7 +383,7 @@ class NewMultiplatformIT : BaseGradleIT() {
             build("printMetadataFiles") {
                 assertSuccessful()
 
-                val expectedFileName = "sample-lib-1.0-${KotlinMultiplatformPlugin.METADATA_TARGET_NAME}.jar"
+                val expectedFileName = "sample-lib-${KotlinMultiplatformPlugin.METADATA_TARGET_NAME}-1.0.jar"
 
                 val paths = metadataDependencyRegex.findAll(output).map { it.groupValues[1] to it.groupValues[2] }.toSet()
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/KotlinTargetConfigurator.kt

@@ -341,7 +341,7 @@ open class KotlinTargetConfigurator<KotlinCompilationType: KotlinCompilation>(
 
         val apiElementsConfiguration = project.configurations.getByName(target.apiElementsConfigurationName)
 
-        target.disambiguationClassifier?.let { jar.classifier = it }
+        target.disambiguationClassifier?.let { jar.appendix = it.toLowerCase() }
 
         // Workaround: adding the artifact during configuration seems to interfere with the Java plugin, which results into missing
         // task dependency 'assemble -> jar' if the Java plugin is applied after this steps

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinMultiplatformPlugin.kt

@@ -94,29 +94,33 @@ class KotlinMultiplatformPlugin(
         val targets = project.multiplatformExtension!!.targets
         val kotlinSoftwareComponent = KotlinSoftwareComponent(project, "kotlin", targets)
 
-        project.afterEvaluate { project -> // Use afterEvaluate because publications configuration is no more lazy since Gradle 4.9
-            project.extensions.configure(PublishingExtension::class.java) { publishing ->
-                // The root publication.
-                publishing.publications.create("kotlin", MavenPublication::class.java) { publication ->
-                    publication.from(kotlinSoftwareComponent)
-                    (publication as MavenPublicationInternal).publishWithOriginalFileName()
-                    publication.artifactId = project.name
-                    publication.groupId = project.group.toString()
-                }
+        project.extensions.configure(PublishingExtension::class.java) { publishing ->
+            // The root publication.
+            publishing.publications.create("kotlinMultiplatform", MavenPublication::class.java).apply {
+                from(kotlinSoftwareComponent)
+                (this as MavenPublicationInternal).publishWithOriginalFileName()
+                artifactId = project.name
+                groupId = project.group.toString()
+                version = project.version.toString()
+            }
 
-                // Create separate publications for all publishable targets
-                kotlinSoftwareComponent.variants.filter { it.publishable }.forEach { variant ->
-                    val coordinates = (variant as? KotlinVariantWithCoordinates)?.coordinates
-                    val name = variant.target.disambiguateName("kotlin")
+            // Create separate publications for all publishable targets
+            targets.matching { it.publishable }.all { target ->
+                val variant = target.component as KotlinVariant
+                val name = target.name
 
-                    publishing.publications.create(name, MavenPublication::class.java) { publication ->
-                        publication.from(variant)
-                        (publication as MavenPublicationInternal).publishWithOriginalFileName()
-                        publication.artifactId = coordinates?.name ?: "${project.name}-${variant.target.name.toLowerCase()}"
-                        publication.groupId = coordinates?.group ?: project.group.toString()
-                        publication.version = coordinates?.version ?: project.version.toString()
+                val variantPublication = publishing.publications.create(name, MavenPublication::class.java).apply {
+                    // do this in afterEvaluate since older Gradle versions seem to check the files in the variant eagerly:
+                    project.afterEvaluate {
+                        from(variant)
                     }
+                    (this as MavenPublicationInternal).publishWithOriginalFileName()
+                    artifactId = "${project.name}-${variant.target.name.toLowerCase()}"
+                    groupId = project.group.toString()
+                    version = project.version.toString()
                 }
+
+                variant.publicationDelegate = variantPublication
             }
         }
 

libraries/tools/kotlin-gradle-plugin/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/KotlinSoftwareComponent.kt

@@ -14,6 +14,7 @@ import org.gradle.api.component.ComponentWithCoordinates
 import org.gradle.api.component.ComponentWithVariants
 import org.gradle.api.internal.component.SoftwareComponentInternal
 import org.gradle.api.internal.component.UsageContext
+import org.gradle.api.publish.maven.MavenPublication
 import org.jetbrains.kotlin.gradle.plugin.KotlinTarget
 import org.jetbrains.kotlin.gradle.plugin.KotlinTargetComponent
 import org.jetbrains.kotlin.gradle.plugin.usageByName
@@ -43,6 +44,10 @@ open class KotlinVariant(
     override fun getUsages(): Set<UsageContext> = target.createUsageContexts()
     override fun getName(): String = target.name
 
+    // This property is declared in the parent class to allow usages to reference it without forcing the subclass to load,
+    // which is needed for compatibility with older Gradle versions
+    internal var publicationDelegate: MavenPublication? = null
+
     override val publishable: Boolean
         get() = target.publishable
 }
@@ -55,12 +60,17 @@ class KotlinVariantWithCoordinates(
     override fun getCoordinates() = object : ModuleVersionIdentifier {
         private val project get() = target.project
 
-        private val moduleName: String get() = "${project.name}-${target.name.toLowerCase()}"
-        private val moduleGroup: String get() = project.group.toString()
+        private val moduleName: String get() =
+            publicationDelegate?.artifactId ?:
+            "${project.name}-${target.name.toLowerCase()}"
+
+        private val moduleGroup: String get() =
+            publicationDelegate?.groupId ?:
+            project.group.toString()
 
         override fun getGroup() = moduleGroup
         override fun getName() = moduleName
-        override fun getVersion() = project.version.toString()
+        override fun getVersion() = publicationDelegate?.version ?: project.version.toString()
 
         override fun getModule(): ModuleIdentifier = object : ModuleIdentifier {
             override fun getGroup(): String = moduleGroup