diff --git a/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurationData.java b/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurationData.java
deleted file mode 100644
index f6a7f95f4e1a..000000000000
--- a/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurationData.java
+++ /dev/null
@@ -1,25 +0,0 @@
-// Copyright 2000-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
-package com.intellij.ide.plugins;
-
-import com.intellij.openapi.extensions.PluginId;
-import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-
-import java.util.Set;
-
-@ApiStatus.Internal
-public final class ClassLoaderConfigurationData {
-  private ClassLoaderConfigurationData() {
-  }
-
-  static final Set<PluginId> SEPARATE_CLASSLOADER_FOR_SUB_EXCLUDE = new ReferenceOpenHashSet<>(new PluginId[]{
-    PluginId.getId("org.jetbrains.kotlin"),
-    PluginId.getId("com.intellij.java"),
-  });
-
-  public static boolean isClassloaderPerDescriptorEnabled(@NotNull PluginId pluginId, @Nullable String packagePrefix) {
-    return packagePrefix != null && !SEPARATE_CLASSLOADER_FOR_SUB_EXCLUDE.contains(pluginId);
-  }
-}
diff --git a/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurator.kt b/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurator.kt
index 18ad3b0fece5..ec24a5b934c7 100644
--- a/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurator.kt
+++ b/platform/core-impl/src/com/intellij/ide/plugins/ClassLoaderConfigurator.kt
@@ -5,6 +5,7 @@ package com.intellij.ide.plugins
 import com.intellij.diagnostic.PluginException
 import com.intellij.ide.plugins.cl.PluginClassLoader
 import com.intellij.openapi.diagnostic.Logger
+import com.intellij.openapi.extensions.PluginId
 import com.intellij.util.SmartList
 import com.intellij.util.lang.ClassPath
 import com.intellij.util.lang.ResourceFile
@@ -27,6 +28,21 @@ class ClassLoaderConfigurator(
   private val coreLoader: ClassLoader = ClassLoaderConfigurator::class.java.classLoader,
   private val usePluginClassLoader: Boolean = true, /* grab classes from platform loader only if nothing is found in any of plugin dependencies */
 ) {
+
+  companion object {
+
+    @ApiStatus.Internal
+    @JvmStatic
+    fun isMigratedToNewModel(idString: String): Boolean {
+      return idString != "org.jetbrains.kotlin"
+             && idString != "com.intellij.java"
+    }
+
+    @ApiStatus.Internal
+    @JvmStatic
+    fun isMigratedToNewModel(pluginId: PluginId) = isMigratedToNewModel(pluginId.idString)
+  }
+
   private var javaDep: Optional<IdeaPluginDescriptorImpl>? = null
 
   // temporary set to produce arrays (avoid allocation for each plugin)
@@ -60,7 +76,8 @@ class ClassLoaderConfigurator(
                                     dependencyPlugin: IdeaPluginDescriptorImpl) {
     for ((mainDependent, modules) in mainToModule) {
       val mainDependentClassLoader = mainDependent.classLoader as PluginClassLoader
-      if (ClassLoaderConfigurationData.isClassloaderPerDescriptorEnabled(mainDependent.id, mainDependent.packagePrefix)) {
+      if (mainDependent.packagePrefix != null
+          && isMigratedToNewModel(mainDependent.id)) {
         for (module in modules) {
           assert(module.packagePrefix != null)
           configureModule(module, mainDependentClassLoader,
diff --git a/platform/platform-impl/src/com/intellij/ide/plugins/DynamicPlugins.kt b/platform/platform-impl/src/com/intellij/ide/plugins/DynamicPlugins.kt
index fd90a5c20f0e..2e3047c0a099 100644
--- a/platform/platform-impl/src/com/intellij/ide/plugins/DynamicPlugins.kt
+++ b/platform/platform-impl/src/com/intellij/ide/plugins/DynamicPlugins.kt
@@ -280,7 +280,8 @@ object DynamicPlugins {
 
     var dependencyMessage: String? = null
     processOptionalDependenciesOnPlugin(descriptor, pluginSet, isLoaded = true) { mainDescriptor, subDescriptor ->
-      if (!ClassLoaderConfigurationData.isClassloaderPerDescriptorEnabled(mainDescriptor.pluginId, subDescriptor.packagePrefix)) {
+      if (subDescriptor.packagePrefix == null
+          || !ClassLoaderConfigurator.isMigratedToNewModel(mainDescriptor.pluginId)) {
         dependencyMessage = "Plugin ${subDescriptor.pluginId} that optionally depends on ${descriptor.pluginId} does not have a separate classloader for the dependency"
         return@processOptionalDependenciesOnPlugin false
       }
diff --git a/plugins/devkit/devkit-core/src/internal/AnalyzeUnloadablePluginsAction.kt b/plugins/devkit/devkit-core/src/internal/AnalyzeUnloadablePluginsAction.kt
index 14b0d559e203..7aa68454492c 100644
--- a/plugins/devkit/devkit-core/src/internal/AnalyzeUnloadablePluginsAction.kt
+++ b/plugins/devkit/devkit-core/src/internal/AnalyzeUnloadablePluginsAction.kt
@@ -1,13 +1,12 @@
-// Copyright 2000-2021 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2021 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.idea.devkit.internal
 
-import com.intellij.ide.plugins.ClassLoaderConfigurationData
+import com.intellij.ide.plugins.ClassLoaderConfigurator
 import com.intellij.ide.plugins.PluginManagerCore
 import com.intellij.openapi.actionSystem.AnAction
 import com.intellij.openapi.actionSystem.AnActionEvent
 import com.intellij.openapi.actionSystem.LangDataKeys
 import com.intellij.openapi.application.runReadAction
-import com.intellij.openapi.extensions.PluginId
 import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.fileEditor.OpenFileDescriptor
 import com.intellij.openapi.progress.ProgressManager
@@ -209,7 +208,8 @@ class AnalyzeUnloadablePluginsAction : AnAction() {
             continue
           }
           descriptor.pluginId?.let { pluginId ->
-            if (!ClassLoaderConfigurationData.isClassloaderPerDescriptorEnabled(PluginId.getId(pluginId), depIdeaPlugin.`package`.rawText)) {
+            if (depIdeaPlugin.`package`.rawText == null
+                || !ClassLoaderConfigurator.isMigratedToNewModel(pluginId)) {
               dependenciesWithoutSeparateClassloaders.add(pluginId)
             }
           }