diff --git a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestDataHolder.java b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestDataHolder.java
index e0c383113423..4401afb81ec7 100644
--- a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestDataHolder.java
+++ b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestDataHolder.java
@@ -9,8 +9,10 @@ import com.intellij.openapi.util.LowMemoryWatcher;
 import com.intellij.util.containers.MultiMap;
 import com.intellij.util.indexing.StorageException;
 import com.intellij.util.io.*;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
 import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
 import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -184,7 +186,7 @@ public final class DiscoveredTestDataHolder {
                              @Nullable String moduleName,
                              byte frameworkId) throws IOException {
     final int testNameId = myTestEnumerator.enumerate(createTestId(testClassName, testMethodName, frameworkId));
-    Int2ObjectOpenHashMap<IntArrayList> result = new Int2ObjectOpenHashMap<>();
+    Int2ObjectMap<IntList> result = new Int2ObjectOpenHashMap<>();
     for (Map.Entry<String, Collection<String>> e : usedMethods.entrySet()) {
       IntArrayList methodIds = new IntArrayList(e.getValue().size());
       result.put(myClassEnumerator.enumerate(e.getKey()), methodIds);
@@ -193,7 +195,7 @@ public final class DiscoveredTestDataHolder {
       }
     }
 
-    Map<Integer, Void> usedVirtualFileIds = new HashMap<>();
+    Int2ObjectMap<Void> usedVirtualFileIds = new Int2ObjectOpenHashMap<>();
     for (String file : usedFiles) {
       if (file.contains("testData") || file.contains("test-data") || file.contains("test_data")) {
         int fileId = myPathEnumerator.enumerate(file);
diff --git a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestsIndex.java b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestsIndex.java
index 724ccf29223c..72ef0b3115fe 100644
--- a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestsIndex.java
+++ b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/DiscoveredTestsIndex.java
@@ -13,13 +13,13 @@ import com.intellij.util.io.DataExternalizer;
 import com.intellij.util.io.EnumeratorIntegerDescriptor;
 import com.intellij.util.io.IntCollectionDataExternalizer;
 import com.intellij.util.io.KeyDescriptor;
-import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.IOException;
 import java.nio.file.Path;
 
-public final class DiscoveredTestsIndex extends MapReduceIndex<Integer, IntArrayList, UsedSources> {
+public final class DiscoveredTestsIndex extends MapReduceIndex<Integer, IntList, UsedSources> {
   DiscoveredTestsIndex(@NotNull Path file) throws IOException {
     super(INDEX_EXTENSION,
           new MyIndexStorage(file),
@@ -41,7 +41,7 @@ public final class DiscoveredTestsIndex extends MapReduceIndex<Integer, IntArray
     return getForwardIndex().get(testId) != null;
   }
 
-  private static class MyIndexStorage extends MapIndexStorage<Integer, IntArrayList> {
+  private static class MyIndexStorage extends MapIndexStorage<Integer, IntList> {
     protected MyIndexStorage(@NotNull Path storageFile) throws IOException {
       super(storageFile, EnumeratorIntegerDescriptor.INSTANCE, IntArrayExternalizer.INSTANCE, 4 * 1024, false);
     }
@@ -52,16 +52,16 @@ public final class DiscoveredTestsIndex extends MapReduceIndex<Integer, IntArray
     }
   }
 
-  private static final IndexExtension<Integer, IntArrayList, UsedSources> INDEX_EXTENSION = new IndexExtension<Integer, IntArrayList, UsedSources>() {
+  private static final IndexExtension<Integer, IntList, UsedSources> INDEX_EXTENSION = new IndexExtension<Integer, IntList, UsedSources>() {
     @NotNull
     @Override
-    public IndexId<Integer, IntArrayList> getName() {
+    public IndexId<Integer, IntList> getName() {
       return IndexId.create("jvm.discovered.tests");
     }
 
     @NotNull
     @Override
-    public DataIndexer<Integer, IntArrayList, UsedSources> getIndexer() {
+    public DataIndexer<Integer, IntList, UsedSources> getIndexer() {
       return inputData -> inputData.myUsedMethods;
     }
 
@@ -73,7 +73,7 @@ public final class DiscoveredTestsIndex extends MapReduceIndex<Integer, IntArray
 
     @NotNull
     @Override
-    public DataExternalizer<IntArrayList> getValueExternalizer() {
+    public DataExternalizer<IntList> getValueExternalizer() {
       return IntArrayExternalizer.INSTANCE;
     }
 
diff --git a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/IntArrayExternalizer.java b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/IntArrayExternalizer.java
index 0b850de40b76..2a00f32d15e7 100644
--- a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/IntArrayExternalizer.java
+++ b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/IntArrayExternalizer.java
@@ -4,20 +4,21 @@ package com.intellij.execution.testDiscovery.indices;
 import com.intellij.util.io.DataExternalizer;
 import com.intellij.util.io.DataInputOutputUtil;
 import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.IntList;
 import org.jetbrains.annotations.NotNull;
 
 import java.io.DataInput;
 import java.io.DataOutput;
 import java.io.IOException;
 
-final class IntArrayExternalizer implements DataExternalizer<IntArrayList> {
+final class IntArrayExternalizer implements DataExternalizer<IntList> {
   static final IntArrayExternalizer INSTANCE = new IntArrayExternalizer();
 
   @Override
-  public void save(@NotNull DataOutput out, IntArrayList value) throws IOException {
+  public void save(@NotNull DataOutput out, IntList value) throws IOException {
     DataInputOutputUtil.writeINT(out, value.size());
     for (int i = 0; i < value.size(); i++) {
-      DataInputOutputUtil.writeINT(out, value.get(i));
+      DataInputOutputUtil.writeINT(out, value.getInt(i));
     }
   }
 
diff --git a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/TestFilesIndex.java b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/TestFilesIndex.java
index a31c49bf3bed..dc58695e6c99 100644
--- a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/TestFilesIndex.java
+++ b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/TestFilesIndex.java
@@ -5,7 +5,8 @@ import com.intellij.openapi.progress.ProgressManager;
 import com.intellij.util.indexing.DataIndexer;
 import com.intellij.util.indexing.IndexExtension;
 import com.intellij.util.indexing.IndexId;
-import com.intellij.util.indexing.impl.*;
+import com.intellij.util.indexing.impl.MapIndexStorage;
+import com.intellij.util.indexing.impl.MapReduceIndex;
 import com.intellij.util.indexing.impl.forward.ForwardIndex;
 import com.intellij.util.indexing.impl.forward.KeyCollectionForwardIndexAccessor;
 import com.intellij.util.indexing.impl.forward.PersistentMapBasedForwardIndex;
@@ -13,7 +14,6 @@ import com.intellij.util.io.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
 import java.util.Collection;
@@ -63,7 +63,9 @@ public class TestFilesIndex extends MapReduceIndex<Integer, Void, UsedSources> {
 
     @NotNull
     @Override
-    public DataIndexer<Integer, Void, UsedSources> getIndexer() {return inputData -> inputData.myUsedFiles;}
+    public DataIndexer<Integer, Void, UsedSources> getIndexer() {
+      return inputData -> inputData.myUsedFiles;
+    }
 
     @NotNull
     @Override
diff --git a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/UsedSources.java b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/UsedSources.java
index a01119313d5c..2b717d69f943 100644
--- a/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/UsedSources.java
+++ b/java/execution/impl/src/com/intellij/execution/testDiscovery/indices/UsedSources.java
@@ -1,19 +1,17 @@
 // Copyright 2000-2020 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.execution.testDiscovery.indices;
 
-import it.unimi.dsi.fastutil.ints.Int2ObjectOpenHashMap;
-import it.unimi.dsi.fastutil.ints.IntArrayList;
+import it.unimi.dsi.fastutil.ints.Int2ObjectMap;
+import it.unimi.dsi.fastutil.ints.IntList;
 import org.jetbrains.annotations.NotNull;
 
-import java.util.Map;
-
 final class UsedSources {
   @NotNull
-  final Int2ObjectOpenHashMap<IntArrayList> myUsedMethods;
+  final Int2ObjectMap<IntList> myUsedMethods;
   @NotNull
-  final Map<Integer, Void> myUsedFiles;
+  final Int2ObjectMap<Void> myUsedFiles;
 
-  UsedSources(@NotNull Int2ObjectOpenHashMap<IntArrayList> methods, @NotNull Map<Integer, Void> files) {
+  UsedSources(@NotNull Int2ObjectMap<IntList> methods, @NotNull Int2ObjectMap<Void> files) {
     myUsedMethods = methods;
     myUsedFiles = files;
   }