diff --git a/platform/util/src/com/intellij/openapi/util/UserDataHolderBase.java b/platform/util/src/com/intellij/openapi/util/UserDataHolderBase.java
index 9e7c6b4dc79b..5a891aab3ace 100644
--- a/platform/util/src/com/intellij/openapi/util/UserDataHolderBase.java
+++ b/platform/util/src/com/intellij/openapi/util/UserDataHolderBase.java
@@ -2,7 +2,6 @@
 package com.intellij.openapi.util;
 
 import com.intellij.ReviseWhenPortedToJDK;
-import com.intellij.openapi.util.userData.ExternalUserDataStorage;
 import com.intellij.util.containers.VarHandleWrapper;
 import com.intellij.util.keyFMap.KeyFMap;
 import com.intellij.util.xmlb.annotations.Transient;
@@ -10,26 +9,12 @@ import org.jetbrains.annotations.*;
 
 import java.io.Serializable;
 import java.util.Objects;
-import java.util.function.Function;
 
 @ReviseWhenPortedToJDK("11") // rewrite to real VarHandles
 @Transient
 public class UserDataHolderBase implements UserDataHolderEx, Serializable {
   private static final Key<KeyFMap> COPYABLE_USER_MAP_KEY = Key.create("COPYABLE_USER_MAP_KEY");
 
-  @Nullable
-  private static Function<@NotNull UserDataHolderBase, @Nullable ExternalUserDataStorage> ourExternalUserDataStorage = null;
-
-  @ApiStatus.Internal
-  public static void setExternalUserDataStorage(@Nullable Function<@NotNull UserDataHolderBase, @Nullable ExternalUserDataStorage> provider) {
-    ourExternalUserDataStorage = provider;
-  }
-
-  private @Nullable ExternalUserDataStorage externalStorage() {
-    Function<@NotNull UserDataHolderBase, @Nullable ExternalUserDataStorage> provider = ourExternalUserDataStorage;
-    return provider == null ? null : provider.apply(this);
-  }
-
   private volatile @NotNull KeyFMap value = KeyFMap.EMPTY_MAP;
   private static final VarHandleWrapper VALUE_HANDLE = VarHandleWrapper.getFactory().create(UserDataHolderBase.class, "value", KeyFMap.class);
 
@@ -62,43 +47,25 @@ public class UserDataHolderBase implements UserDataHolderEx, Serializable {
 
   @Override
   public <T> T getUserData(@NotNull Key<T> key) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      return external.getUserData(this, key);
-    }
-    else {
-      T t = getUserMap().get(key);
-      if (t == null && key instanceof KeyWithDefaultValue) {
-        t = putUserDataIfAbsent(key, ((KeyWithDefaultValue<T>)key).getDefaultValue());
-      }
-      return t;
+    T t = getUserMap().get(key);
+    if (t == null && key instanceof KeyWithDefaultValue) {
+      t = putUserDataIfAbsent(key, ((KeyWithDefaultValue<T>)key).getDefaultValue());
     }
+    return t;
   }
 
   @ApiStatus.Internal
   public @NotNull KeyFMap getUserMap() {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      return external.getUserMap(this);
-    }
-    else {
-      return value;
-    }
+    return value;
   }
 
   @Override
   public <T> void putUserData(@NotNull Key<T> key, @Nullable T value) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      external.putUserData(this, key, value);
-    }
-    else {
-      while (true) {
-        KeyFMap map = getUserMap();
-        KeyFMap newMap = value == null ? map.minus(key) : map.plus(key, value);
-        if (newMap == map || changeUserMap(map, newMap)) {
-          break;
-        }
+    while (true) {
+      KeyFMap map = getUserMap();
+      KeyFMap newMap = value == null ? map.minus(key) : map.plus(key, value);
+      if (newMap == map || changeUserMap(map, newMap)) {
+        break;
       }
     }
   }
@@ -113,88 +80,45 @@ public class UserDataHolderBase implements UserDataHolderEx, Serializable {
   }
 
   public <T> void putCopyableUserData(@NotNull Key<T> key, T value) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      while (true) {
-        KeyFMap oldCopyableMap = getUserData(COPYABLE_USER_MAP_KEY);
-        KeyFMap newCopyableMap = oldCopyableMap;
-        if (oldCopyableMap == null) {
-          if (value == null) {
-            //nothing
-          }
-          else {
-            newCopyableMap = KeyFMap.EMPTY_MAP.plus(key, value);
-          }
-        }
-        else {
-          if (value == null) {
-            newCopyableMap = oldCopyableMap.minus(key);
-          }
-          else {
-            newCopyableMap = oldCopyableMap.plus(key, value);
-          }
-        }
-        if (
-          oldCopyableMap == newCopyableMap ||
-          external.compareAndPutUserData(this, COPYABLE_USER_MAP_KEY, oldCopyableMap, newCopyableMap)
-        ) {
-          break;
-        }
+    while (true) {
+      KeyFMap map = getUserMap();
+      KeyFMap copyableMap = map.get(COPYABLE_USER_MAP_KEY);
+      if (copyableMap == null) {
+        copyableMap = KeyFMap.EMPTY_MAP;
       }
-    }
-    else {
-      while (true) {
-        KeyFMap map = getUserMap();
-        KeyFMap copyableMap = map.get(COPYABLE_USER_MAP_KEY);
-        if (copyableMap == null) {
-          copyableMap = KeyFMap.EMPTY_MAP;
-        }
-        KeyFMap newCopyableMap = value == null ? copyableMap.minus(key) : copyableMap.plus(key, value);
-        KeyFMap newMap = newCopyableMap.isEmpty() ? map.minus(COPYABLE_USER_MAP_KEY) : map.plus(COPYABLE_USER_MAP_KEY, newCopyableMap);
-        if (newMap == map || changeUserMap(map, newMap)) {
-          return;
-        }
+      KeyFMap newCopyableMap = value == null ? copyableMap.minus(key) : copyableMap.plus(key, value);
+      KeyFMap newMap = newCopyableMap.isEmpty() ? map.minus(COPYABLE_USER_MAP_KEY) : map.plus(COPYABLE_USER_MAP_KEY, newCopyableMap);
+      if (newMap == map || changeUserMap(map, newMap)) {
+        return;
       }
     }
   }
 
   @Override
   public <T> boolean replace(@NotNull Key<T> key, @Nullable T oldValue, @Nullable T newValue) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      return external.compareAndPutUserData(this, key, oldValue, newValue);
-    }
-    else {
-      while (true) {
-        KeyFMap map = getUserMap();
-        if (map.get(key) != oldValue) {
-          return false;
-        }
-        KeyFMap newMap = newValue == null ? map.minus(key) : map.plus(key, newValue);
-        if (newMap == map || changeUserMap(map, newMap)) {
-          return true;
-        }
+    while (true) {
+      KeyFMap map = getUserMap();
+      if (map.get(key) != oldValue) {
+        return false;
+      }
+      KeyFMap newMap = newValue == null ? map.minus(key) : map.plus(key, newValue);
+      if (newMap == map || changeUserMap(map, newMap)) {
+        return true;
       }
     }
   }
 
   @Override
   public @NotNull <T> T putUserDataIfAbsent(final @NotNull Key<T> key, final @NotNull T value) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      return external.putUserDataIfAbsent(this, key, value);
-    }
-    else {
-      while (true) {
-        KeyFMap map = getUserMap();
-        T oldValue = map.get(key);
-        if (oldValue != null) {
-          return oldValue;
-        }
-        KeyFMap newMap = map.plus(key, value);
-        if (newMap == map || changeUserMap(map, newMap)) {
-          return value;
-        }
+    while (true) {
+      KeyFMap map = getUserMap();
+      T oldValue = map.get(key);
+      if (oldValue != null) {
+        return oldValue;
+      }
+      KeyFMap newMap = map.plus(key, value);
+      if (newMap == map || changeUserMap(map, newMap)) {
+        return value;
       }
     }
   }
@@ -213,13 +137,7 @@ public class UserDataHolderBase implements UserDataHolderEx, Serializable {
   }
 
   protected void setUserMap(@NotNull KeyFMap map) {
-    ExternalUserDataStorage external = externalStorage();
-    if (external != null) {
-      external.setUserMap(this, map);
-    }
-    else {
-      value = map;
-    }
+    value = map;
   }
 
   public boolean isUserDataEmpty() {
diff --git a/platform/util/src/com/intellij/openapi/util/userData/ExternalUserDataStorage.kt b/platform/util/src/com/intellij/openapi/util/userData/ExternalUserDataStorage.kt
deleted file mode 100644
index ea2857645f43..000000000000
--- a/platform/util/src/com/intellij/openapi/util/userData/ExternalUserDataStorage.kt
+++ /dev/null
@@ -1,22 +0,0 @@
-package com.intellij.openapi.util.userData
-
-import com.intellij.openapi.util.Key
-import com.intellij.openapi.util.UserDataHolder
-import com.intellij.util.keyFMap.KeyFMap
-import org.jetbrains.annotations.ApiStatus
-
-@ApiStatus.Internal
-interface ExternalUserDataStorage {
-
-  fun <T : Any> getUserData(obj: UserDataHolder, key: Key<T>): T?
-
-  fun <T : Any> putUserData(obj: UserDataHolder, key: Key<T>, value: T?)
-
-  fun <T : Any> compareAndPutUserData(obj: UserDataHolder, key: Key<T>, oldValue: T?, newValue: T?): Boolean
-
-  fun getUserMap(obj: UserDataHolder): KeyFMap
-
-  fun setUserMap(obj: UserDataHolder, userMap: KeyFMap)
-
-  fun <T : Any> putUserDataIfAbsent(obj: UserDataHolder, key: Key<T>, value: T): T
-}
\ No newline at end of file