added helper class to workaround KT-9670

platform/configuration-store-impl/src/StateStorageManagerImpl.kt

@@ -130,7 +130,8 @@ open class StateStorageManagerImpl(private val rootTagName: String,
     }
   }
 
-  override final fun getStateStorage(storageSpec: Storage) = getOrCreateStorage(storageSpec.file, storageSpec.roamingType, storageSpec.storageClass.java as Class<out StateStorage>, storageSpec.stateSplitter.java)
+  override final fun getStateStorage(storageSpec: Storage) = getOrCreateStorage(storageSpec.file, storageSpec.roamingType,
+          JavaAnnotationHelperForKotlin.getStorageClass(storageSpec), JavaAnnotationHelperForKotlin.getStateSplitterClass(storageSpec))
 
   protected open fun normalizeFileSpec(fileSpec: String): String {
     val path = FileUtilRt.toSystemIndependentName(fileSpec)

platform/configuration-store-impl/src/com/intellij/configurationStore/JavaAnnotationHelperForKotlin.java

@@ -0,0 +1,20 @@
+package com.intellij.configurationStore;
+
+import com.intellij.openapi.components.StateSplitter;
+import com.intellij.openapi.components.StateStorage;
+import com.intellij.openapi.components.Storage;
+
+/**
+ * This class was introduced as a workaround for Kotlin bug (https://youtrack.jetbrains.com/issue/KT-9670) to avoid creation of
+ * unnecessary instances of KClass
+ * todo[nik] remove when KT-9670 is fixed
+ */
+public class JavaAnnotationHelperForKotlin {
+  public static Class<? extends StateStorage> getStorageClass(Storage storage) {
+    return storage.storageClass();
+  }
+
+  public static Class<? extends StateSplitter> getStateSplitterClass(Storage storage) {
+    return storage.stateSplitter();
+  }
+}