diff --git a/libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainer.kt b/libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainer.kt
index d9e3104e24c..c874a76fbd1 100644
--- a/libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainer.kt
+++ b/libraries/tools/kotlin-gradle-plugin-idea/src/main/kotlin/org/jetbrains/kotlin/gradle/kpm/KotlinExternalModelContainer.kt
@@ -8,7 +8,7 @@ package org.jetbrains.kotlin.gradle.kpm
 import org.jetbrains.kotlin.gradle.kpm.idea.InternalKotlinGradlePluginApi
 import java.io.Serializable
 
-abstract class KotlinExternalModelContainer internal constructor() : Serializable {
+sealed class KotlinExternalModelContainer() : Serializable {
     abstract val ids: Set<KotlinExternalModelId<*>>
     abstract operator fun <T : Any> contains(key: KotlinExternalModelKey<T>): Boolean
     abstract operator fun <T : Any> get(key: KotlinExternalModelKey<T>): T?
@@ -31,6 +31,6 @@ abstract class KotlinExternalModelContainer internal constructor() : Serializabl
     }
 }
 
-abstract class KotlinMutableExternalModelContainer internal constructor() : KotlinExternalModelContainer() {
+sealed class KotlinMutableExternalModelContainer : KotlinExternalModelContainer() {
     abstract operator fun <T : Any> set(key: KotlinExternalModelKey<T>, value: T)
 }