Fix creation of empty source sets in tests

idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/ExternalSystemImportingTestCase.java

@@ -200,7 +200,8 @@ public abstract class ExternalSystemImportingTestCase extends ExternalSystemTest
 
         final Ref<Couple<String>> error = Ref.create();
         ExternalSystemUtil.refreshProjects(
-                new ImportSpecBuilder(myProject, getExternalSystemId())
+                new TestImportSpecBuilder(myProject, getExternalSystemId())
+                        .setCreateEmptyContentRoots(projectSettings.isCreateEmptyContentRootDirectories())
                         .use(ProgressExecutionMode.MODAL_SYNC)
                         .callback(new ExternalProjectRefreshCallback() {
                             @Override

idea/idea-gradle/tests/org/jetbrains/kotlin/idea/codeInsight/gradle/TestImportSpecBuilder.java

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2019 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.idea.codeInsight.gradle;
+
+import com.intellij.openapi.externalSystem.importing.ImportSpec;
+import com.intellij.openapi.externalSystem.importing.ImportSpecBuilder;
+import com.intellij.openapi.externalSystem.model.ProjectSystemId;
+import com.intellij.openapi.project.Project;
+import org.jetbrains.annotations.NotNull;
+
+public class TestImportSpecBuilder extends ImportSpecBuilder {
+    public TestImportSpecBuilder(
+            @NotNull Project project,
+            @NotNull ProjectSystemId id
+    ) {
+        super(project, id);
+    }
+
+    public ImportSpecBuilder setCreateEmptyContentRoots(boolean value) {
+        return createDirectoriesForEmptyContentRoots();
+    }
+}