[Gradle][KPM] Reference Configurations directly

Configurations are not registered/created lazily which makes
referencing NamedDomainObjectProvider over Configurations unnecessary
for now.

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/KotlinDependencyConfigurations.kt

@@ -9,34 +9,34 @@ import org.gradle.api.NamedDomainObjectProvider
 import org.gradle.api.artifacts.Configuration
 
 interface KotlinDependencyConfigurations {
-    val apiConfiguration: NamedDomainObjectProvider<Configuration>
-    val implementationConfiguration: NamedDomainObjectProvider<Configuration>
-    val compileOnlyConfiguration: NamedDomainObjectProvider<Configuration>
-    val runtimeOnlyConfiguration: NamedDomainObjectProvider<Configuration>
+    val apiConfiguration: Configuration
+    val implementationConfiguration: Configuration
+    val compileOnlyConfiguration: Configuration
+    val runtimeOnlyConfiguration: Configuration
 
     /** This configuration includes the dependencies from the refines-parents */
-    val transitiveApiConfiguration: NamedDomainObjectProvider<Configuration>
+    val transitiveApiConfiguration: Configuration
 
     /** This configuration includes the dependencies from the refines-parents */
-    val transitiveImplementationConfiguration: NamedDomainObjectProvider<Configuration>
+    val transitiveImplementationConfiguration: Configuration
 
     private class Impl(
-        override val apiConfiguration: NamedDomainObjectProvider<Configuration>,
-        override val implementationConfiguration: NamedDomainObjectProvider<Configuration>,
-        override val compileOnlyConfiguration: NamedDomainObjectProvider<Configuration>,
-        override val runtimeOnlyConfiguration: NamedDomainObjectProvider<Configuration>,
-        override val transitiveApiConfiguration: NamedDomainObjectProvider<Configuration>,
-        override val transitiveImplementationConfiguration: NamedDomainObjectProvider<Configuration>
+        override val apiConfiguration: Configuration,
+        override val implementationConfiguration: Configuration,
+        override val compileOnlyConfiguration: Configuration,
+        override val runtimeOnlyConfiguration: Configuration,
+        override val transitiveApiConfiguration:Configuration,
+        override val transitiveImplementationConfiguration: Configuration
     ) : KotlinDependencyConfigurations
 
     companion object {
         fun create(
-            apiConfiguration: NamedDomainObjectProvider<Configuration>,
-            implementationConfiguration: NamedDomainObjectProvider<Configuration>,
-            compileOnlyConfiguration: NamedDomainObjectProvider<Configuration>,
-            runtimeOnlyConfiguration: NamedDomainObjectProvider<Configuration>,
-            transitiveApiConfiguration: NamedDomainObjectProvider<Configuration>,
-            transitiveImplementationConfiguration: NamedDomainObjectProvider<Configuration>
+            apiConfiguration: Configuration,
+            implementationConfiguration: Configuration,
+            compileOnlyConfiguration: Configuration,
+            runtimeOnlyConfiguration: Configuration,
+            transitiveApiConfiguration: Configuration,
+            transitiveImplementationConfiguration: Configuration
         ): KotlinDependencyConfigurations = Impl(
             apiConfiguration = apiConfiguration,
             implementationConfiguration = implementationConfiguration,

libraries/tools/kotlin-gradle-plugin-api/src/main/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/pm20/KotlinGradleVariant.kt

@@ -18,7 +18,7 @@ interface KotlinGradleVariant : KotlinGradleFragment, KotlinModuleVariant {
     val platformType: KotlinPlatformType
 
     // TODO generalize with KotlinCompilation?
-    val compileDependenciesConfiguration: NamedDomainObjectProvider<Configuration>
+    val compileDependenciesConfiguration: Configuration
 
     var compileDependencyFiles: FileCollection
 
@@ -29,28 +29,28 @@ interface KotlinGradleVariant : KotlinGradleFragment, KotlinModuleVariant {
     val sourceArchiveTaskName: String
 
     // TODO generalize exposing outputs: what if a variant has more than one such configurations or none?
-    val apiElementsConfiguration: NamedDomainObjectProvider<Configuration>
+    val apiElementsConfiguration: Configuration
 
     val gradleVariantNames: Set<String>
 }
 
 interface KotlinGradleVariantWithRuntime : KotlinGradleVariant {
     // TODO deduplicate with KotlinCompilation?
-    val runtimeDependenciesConfiguration: NamedDomainObjectProvider<Configuration>
+    val runtimeDependenciesConfiguration: Configuration
 
     var runtimeDependencyFiles: FileCollection
 
     val runtimeFiles: ConfigurableFileCollection
 
     // TODO generalize exposing outputs: what if a variant has more than one such configurations or none?
-    val runtimeElementsConfiguration: NamedDomainObjectProvider<Configuration>
+    val runtimeElementsConfiguration: Configuration
 }
 
 interface KotlinNativeVariant : KotlinGradleVariant {
     override val platformType: KotlinPlatformType
         get() = KotlinPlatformType.native
 
-    val hostSpecificMetadataElementsConfiguration: NamedDomainObjectProvider<Configuration>?
+    val hostSpecificMetadataElementsConfiguration: Configuration?
 
     var enableEndorsedLibraries: Boolean
 }