diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JdkAndMockLibraryProjectDescriptor.java b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JdkAndMockLibraryProjectDescriptor.java
index c472d7517bc..760158f0e7b 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JdkAndMockLibraryProjectDescriptor.java
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JdkAndMockLibraryProjectDescriptor.java
@@ -22,6 +22,7 @@ import com.intellij.openapi.roots.ModifiableRootModel;
 import com.intellij.openapi.roots.OrderRootType;
 import com.intellij.openapi.roots.libraries.Library;
 import com.intellij.openapi.util.io.FileUtilRt;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.kotlin.test.MockLibraryUtil;
 
 import java.io.File;
@@ -44,7 +45,7 @@ public class JdkAndMockLibraryProjectDescriptor extends JetLightProjectDescripto
     }
 
     @Override
-    public void configureModule(Module module, ModifiableRootModel model, ContentEntry contentEntry) {
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model) {
         File libraryJar = MockLibraryUtil.compileLibraryToJar(sourcesPath, LIBRARY_NAME, withSources, isJsLibrary);
         String jarUrl = "jar://" + FileUtilRt.toSystemIndependentName(libraryJar.getAbsolutePath()) + "!/";
 
diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetJdkAndLibraryProjectDescriptor.java b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetJdkAndLibraryProjectDescriptor.java
index 73491407797..9844d686bd0 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetJdkAndLibraryProjectDescriptor.java
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetJdkAndLibraryProjectDescriptor.java
@@ -31,7 +31,7 @@ import org.jetbrains.annotations.Nullable;
 
 import java.io.File;
 
-public class JetJdkAndLibraryProjectDescriptor implements LightProjectDescriptor {
+public class JetJdkAndLibraryProjectDescriptor extends JetLightProjectDescriptor {
     public static final String LIBRARY_NAME = "myLibrary";
 
     private final File libraryFile;
@@ -52,7 +52,7 @@ public class JetJdkAndLibraryProjectDescriptor implements LightProjectDescriptor
     }
 
     @Override
-    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model, @Nullable ContentEntry contentEntry) {
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model) {
         NewLibraryEditor editor = new NewLibraryEditor();
         editor.setName(LIBRARY_NAME);
         editor.addRoot(VfsUtil.getUrlForLibraryRoot(libraryFile), OrderRootType.CLASSES);
diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetLightProjectDescriptor.java b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetLightProjectDescriptor.java
index db6e7aecbd1..a64ef540f50 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetLightProjectDescriptor.java
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/JetLightProjectDescriptor.java
@@ -23,6 +23,7 @@ import com.intellij.openapi.projectRoots.Sdk;
 import com.intellij.openapi.roots.ContentEntry;
 import com.intellij.openapi.roots.ModifiableRootModel;
 import com.intellij.testFramework.LightProjectDescriptor;
+import org.jetbrains.annotations.NotNull;
 
 public class JetLightProjectDescriptor implements LightProjectDescriptor {
     protected JetLightProjectDescriptor() {
@@ -41,6 +42,10 @@ public class JetLightProjectDescriptor implements LightProjectDescriptor {
     }
 
     @Override
-    public void configureModule(Module module, ModifiableRootModel model, ContentEntry contentEntry) {
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model, @NotNull ContentEntry contentEntry) {
+        configureModule(module, model);
+    }
+
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model) {
     }
 }
diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/KotlinStdJSProjectDescriptor.kt b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/KotlinStdJSProjectDescriptor.kt
index 028308dec21..3e7d6216956 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/KotlinStdJSProjectDescriptor.kt
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/KotlinStdJSProjectDescriptor.kt
@@ -18,7 +18,7 @@ package org.jetbrains.kotlin.idea.test
 
 import com.intellij.testFramework.LightProjectDescriptor
 
-public trait KotlinStdJSProjectDescriptor : LightProjectDescriptor {
+public open class KotlinStdJSProjectDescriptor : JetLightProjectDescriptor() {
     companion object {
         public val instance: KotlinStdJSProjectDescriptor
                 = Class.forName("org.jetbrains.kotlin.test.KotlinStdJSProjectDescriptorImpl").newInstance() as KotlinStdJSProjectDescriptor
diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/ProjectDescriptorWithStdlibSources.java b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/ProjectDescriptorWithStdlibSources.java
index 729db3c2f10..d32e8fe9610 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/ProjectDescriptorWithStdlibSources.java
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/ProjectDescriptorWithStdlibSources.java
@@ -31,8 +31,8 @@ public class ProjectDescriptorWithStdlibSources extends JetWithJdkAndRuntimeLigh
     public static final ProjectDescriptorWithStdlibSources INSTANCE = new ProjectDescriptorWithStdlibSources();
 
     @Override
-    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model, @Nullable ContentEntry contentEntry) {
-        super.configureModule(module, model, contentEntry);
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model) {
+        super.configureModule(module, model);
 
         Library library = model.getModuleLibraryTable().getLibraryByName(LIBRARY_NAME);
         assert library != null;
diff --git a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/testUtils.kt b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/testUtils.kt
index f2ceee92f56..d947a9b4a7a 100644
--- a/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/testUtils.kt
+++ b/idea/idea-test-framework/src/org/jetbrains/kotlin/idea/test/testUtils.kt
@@ -37,7 +37,7 @@ public enum class ModuleKind {
     KOTLIN_JAVASCRIPT
 }
 
-public fun Module.configureAs(descriptor: LightProjectDescriptor) {
+public fun Module.configureAs(descriptor: JetLightProjectDescriptor) {
     val module = this
     updateModel(module, object : Consumer<ModifiableRootModel> {
         override fun consume(model: ModifiableRootModel) {
@@ -45,8 +45,12 @@ public fun Module.configureAs(descriptor: LightProjectDescriptor) {
                 model.setSdk(descriptor.getSdk())
             }
             val entries = model.getContentEntries()
-            val entry = if (entries.size() > 0) entries[0] else null
-            descriptor.configureModule(module, model, entry)
+            if (entries.isEmpty()) {
+                descriptor.configureModule(module, model)
+            }
+            else {
+                descriptor.configureModule(module, model, entries[0])
+            }
         }
     })
 }
diff --git a/idea/tests/org/jetbrains/kotlin/idea/caches/resolve/HighlightingWithDependentLibrariesTest.kt b/idea/tests/org/jetbrains/kotlin/idea/caches/resolve/HighlightingWithDependentLibrariesTest.kt
index 36c1b868536..c60491c2b8e 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/caches/resolve/HighlightingWithDependentLibrariesTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/caches/resolve/HighlightingWithDependentLibrariesTest.kt
@@ -33,7 +33,7 @@ public class HighlightingWithDependentLibrariesTest : JetLightCodeInsightFixture
     private val TEST_DATA_PATH = PluginTestCaseBase.getTestDataPathBase() + "/highlightingWithDependentLibraries"
 
     override fun getProjectDescriptor() = object : JetLightProjectDescriptor() {
-        override fun configureModule(module: Module, model: ModifiableRootModel, contentEntry: ContentEntry?) {
+        override fun configureModule(module: Module, model: ModifiableRootModel) {
             val compiledJar1 = MockLibraryUtil.compileLibraryToJar("$TEST_DATA_PATH/lib1", "lib1", false)
             val compiledJar2 = MockLibraryUtil.compileLibraryToJar("$TEST_DATA_PATH/lib2", "lib2", false, compiledJar1.canonicalPath)
 
diff --git a/idea/tests/org/jetbrains/kotlin/idea/debugger/KotlinDebuggerTestCase.java b/idea/tests/org/jetbrains/kotlin/idea/debugger/KotlinDebuggerTestCase.java
index a48c43c5cf4..1a7d660dbbc 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/debugger/KotlinDebuggerTestCase.java
+++ b/idea/tests/org/jetbrains/kotlin/idea/debugger/KotlinDebuggerTestCase.java
@@ -84,7 +84,7 @@ public abstract class KotlinDebuggerTestCase extends DescriptorTestCase {
                     public void run() {
                         ModifiableRootModel model = ModuleRootManager.getInstance(getModule()).getModifiableModel();
 
-                        projectDescriptor.configureModule(getModule(), model, null);
+                        projectDescriptor.configureModule(getModule(), model);
 
                         VirtualFile customLibrarySources = VfsUtil.findFileByIoFile(CUSTOM_LIBRARY_SOURCES, false);
                         assert customLibrarySources != null : "VirtualFile for customLibrary sources should be found";
diff --git a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/CodeFragmentCompletionInLibraryTest.kt b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/CodeFragmentCompletionInLibraryTest.kt
index 55b099baf48..fbbd39144f8 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/CodeFragmentCompletionInLibraryTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/debugger/evaluate/CodeFragmentCompletionInLibraryTest.kt
@@ -39,8 +39,8 @@ private val LIBRARY_SRC_PATH = JetTestUtils.getHomeDirectory() + "/idea/idea-com
 public class CodeFragmentCompletionInLibraryTest : AbstractJvmBasicCompletionTest() {
 
     override fun getProjectDescriptor() = object: JdkAndMockLibraryProjectDescriptor(LIBRARY_SRC_PATH, false) {
-        override fun configureModule(module: Module, model: ModifiableRootModel, contentEntry: ContentEntry?) {
-            super.configureModule(module, model, contentEntry)
+        override fun configureModule(module: Module, model: ModifiableRootModel) {
+            super.configureModule(module, model)
 
             val library = model.getModuleLibraryTable().getLibraryByName(JdkAndMockLibraryProjectDescriptor.LIBRARY_NAME)!!
             val modifiableModel = library.getModifiableModel()
diff --git a/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt b/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
index 01969b22337..007a0c0f3b2 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
+++ b/idea/tests/org/jetbrains/kotlin/idea/decompiler/navigation/AbstractNavigateToLibrarySourceTest.kt
@@ -107,6 +107,6 @@ public abstract class AbstractNavigateToLibrarySourceTest : KotlinCodeInsightTes
         return JetTestUtils.getLastCommentedLines(document)
     }
 
-    private fun getProjectDescriptor(): LightProjectDescriptor =
+    private fun getProjectDescriptor(): JetLightProjectDescriptor =
             JdkAndMockLibraryProjectDescriptor(PluginTestCaseBase.getTestDataPathBase() + "/decompiler/navigation/library", true)
 }
\ No newline at end of file
diff --git a/idea/tests/org/jetbrains/kotlin/test/KotlinStdJSProjectDescriptorImpl.java b/idea/tests/org/jetbrains/kotlin/test/KotlinStdJSProjectDescriptorImpl.java
index 27ab2cb0817..42bdc4bbaf7 100644
--- a/idea/tests/org/jetbrains/kotlin/test/KotlinStdJSProjectDescriptorImpl.java
+++ b/idea/tests/org/jetbrains/kotlin/test/KotlinStdJSProjectDescriptorImpl.java
@@ -20,16 +20,15 @@ import com.intellij.openapi.module.Module;
 import com.intellij.openapi.module.ModuleType;
 import com.intellij.openapi.module.StdModuleTypes;
 import com.intellij.openapi.projectRoots.Sdk;
-import com.intellij.openapi.roots.ContentEntry;
 import com.intellij.openapi.roots.ModifiableRootModel;
 import com.intellij.openapi.roots.libraries.NewLibraryConfiguration;
 import com.intellij.openapi.roots.ui.configuration.libraryEditor.NewLibraryEditor;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.kotlin.idea.test.KotlinStdJSProjectDescriptor;
 import org.jetbrains.kotlin.idea.framework.JSLibraryStdDescription;
 import org.jetbrains.kotlin.idea.test.ConfigLibraryUtil;
+import org.jetbrains.kotlin.idea.test.KotlinStdJSProjectDescriptor;
 
-public class KotlinStdJSProjectDescriptorImpl implements KotlinStdJSProjectDescriptor {
+public class KotlinStdJSProjectDescriptorImpl extends KotlinStdJSProjectDescriptor {
     @Override
     public ModuleType getModuleType() {
         return StdModuleTypes.JAVA;
@@ -41,7 +40,7 @@ public class KotlinStdJSProjectDescriptorImpl implements KotlinStdJSProjectDescr
     }
 
     @Override
-    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model, ContentEntry contentEntry) {
+    public void configureModule(@NotNull Module module, @NotNull ModifiableRootModel model) {
         NewLibraryConfiguration configuration = new JSLibraryStdDescription(module.getProject()).createNewLibraryForTests();
 
         assert configuration != null : "Configuration should exist";