[Gradle] rework addSourceSet to not let sourceSets be exposed in groovy

Also mark it as deprecated to prevent internal misuses.

^KT-58234 Verification Pending

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/AbstractKotlinPlugin.kt

@@ -194,6 +194,7 @@ internal abstract class AbstractKotlinPlugin(
                     javaSourceSet.resources.setSrcDirs(
                         listOf { kotlinSourceSet.resources.sourceDirectories }
                     )
+                    @Suppress("DEPRECATION")
                     kotlinCompilation.addSourceSet(kotlinSourceSet)
                     project.compatibilityConventionRegistrar.addConvention(javaSourceSet, kotlinSourceSetDslName, kotlinSourceSet)
                     javaSourceSet.addExtension(kotlinSourceSetDslName, kotlinSourceSet.kotlin)
@@ -204,6 +205,7 @@ internal abstract class AbstractKotlinPlugin(
             }
 
             kotlinTarget.compilations.all { kotlinCompilation ->
+                @Suppress("DEPRECATION")
                 kotlinCompilation.addSourceSet(kotlinCompilation.defaultSourceSet)
             }
 

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

@@ -100,6 +100,7 @@ abstract class AbstractKotlinTargetConfigurator<KotlinTargetType : KotlinTarget>
 
     override fun configureSourceSet(target: KotlinTargetType) {
         target.compilations.all { compilation ->
+            @Suppress("DEPRECATION")
             compilation.addSourceSet(compilation.defaultSourceSet) // also adds dependencies, requires the configurations for target and source set to exist at this point
         }
     }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/InternalKotlinCompilation.kt

@@ -6,16 +6,17 @@
 package org.jetbrains.kotlin.gradle.plugin.mpp
 
 import org.gradle.api.file.FileCollection
+import org.jetbrains.kotlin.gradle.InternalKotlinGradlePluginApi
 import org.jetbrains.kotlin.gradle.dsl.KotlinCommonOptions
 import org.jetbrains.kotlin.gradle.plugin.KotlinCompilation
 import org.jetbrains.kotlin.gradle.plugin.KotlinPluginLifecycle
 import org.jetbrains.kotlin.gradle.plugin.KotlinSourceSet
 import org.jetbrains.kotlin.gradle.plugin.await
 import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinCompilationConfigurationsContainer
-import org.jetbrains.kotlin.gradle.plugin.mpp.compilationImpl.KotlinCompilationSourceSetsContainer
 import org.jetbrains.kotlin.gradle.utils.ObservableSet
 import org.jetbrains.kotlin.tooling.core.HasMutableExtras
 
+@InternalKotlinGradlePluginApi
 internal interface InternalKotlinCompilation<out T : KotlinCommonOptions> : KotlinCompilation<T>, HasMutableExtras {
     override val kotlinSourceSets: ObservableSet<KotlinSourceSet>
     override val allKotlinSourceSets: ObservableSet<KotlinSourceSet>
@@ -23,7 +24,6 @@ internal interface InternalKotlinCompilation<out T : KotlinCommonOptions> : Kotl
     val configurations: KotlinCompilationConfigurationsContainer
     val friendPaths: Iterable<FileCollection>
     val processResourcesTaskName: String?
-    val sourceSets: KotlinCompilationSourceSetsContainer
 }
 
 internal val <T : KotlinCommonOptions> KotlinCompilation<T>.internal: InternalKotlinCompilation<T>
@@ -36,5 +36,7 @@ internal suspend fun InternalKotlinCompilation<*>.awaitAllKotlinSourceSets(): Se
     return allKotlinSourceSets
 }
 
-internal fun KotlinCompilation<*>.addSourceSet(kotlinSourceSet: KotlinSourceSet) =
-    internal.sourceSets.source(kotlinSourceSet)
+@Deprecated("KT-58234: Adding source sets to Compilation is not recommended. Please consider using dependsOn.")
+internal fun KotlinCompilation<*>.addSourceSet(kotlinSourceSet: KotlinSourceSet) {
+    internal.decoratedInstance.compilation.sourceSets.source(kotlinSourceSet)
+}

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/plugin/mpp/compilationImpl/KotlinCompilationImpl.kt

@@ -59,7 +59,7 @@ internal class KotlinCompilationImpl constructor(
 
     override val extras: MutableExtras = mutableExtrasOf()
 
-    override val sourceSets get() = params.sourceSets
+    val sourceSets get() = params.sourceSets
 
     override val configurations: KotlinCompilationConfigurationsContainer
         get() = params.dependencyConfigurations

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/android/AndroidProjectHandler.kt

@@ -206,9 +206,11 @@ internal class AndroidProjectHandler(
         }
 
         // Register the source only after the task is created, because the task is required for that:
+        @Suppress("DEPRECATION")
         compilation.addSourceSet(defaultSourceSet)
 
         compilation.androidVariant.forEachKotlinSourceSet(project) { kotlinSourceSet ->
+            @Suppress("DEPRECATION")
             compilation.addSourceSet(kotlinSourceSet)
         }
     }

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/js/KotlinJsTargetConfigurator.kt

@@ -62,6 +62,7 @@ open class KotlinJsTargetConfigurator :
         val project = target.project
 
         target.compilations.all { compilation ->
+            @Suppress("DEPRECATION")
             compilation.addSourceSet(compilation.defaultSourceSet)
 
             configureResourceProcessing(

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/metadata/KotlinMetadataTargetConfigurator.kt

@@ -79,6 +79,7 @@ class KotlinMetadataTargetConfigurator :
                     // it isn't necessary for KLib compilations
                     // see [KotlinCompilationSourceSetInclusion.AddSourcesWithoutDependsOnClosure]
                     defaultSourceSet.internal.dependsOnClosure.forAll {
+                        @Suppress("DEPRECATION")
                         addSourceSet(it)
                     }
                 } else {

libraries/tools/kotlin-gradle-plugin/src/common/kotlin/org/jetbrains/kotlin/gradle/targets/metadata/KotlinMetadataTargetPreset.kt

@@ -54,6 +54,7 @@ class KotlinMetadataTargetPreset(
             val mainCompilation = compilations.getByName(KotlinCompilation.MAIN_COMPILATION_NAME)
             val commonMainSourceSet = project.kotlinExtension.sourceSets.getByName(KotlinSourceSet.COMMON_MAIN_SOURCE_SET_NAME)
 
+            @Suppress("DEPRECATION")
             mainCompilation.addSourceSet(commonMainSourceSet)
 
             project.whenEvaluated {