Invalidate module source roots in create actual to fix exceptions

Related to KT-19586

idea/idea-core/src/org/jetbrains/kotlin/idea/core/packageUtils.kt

@@ -21,6 +21,7 @@ import org.jetbrains.jps.model.java.JavaSourceRootProperties
 import org.jetbrains.jps.model.module.JpsModuleSourceRootType
 import org.jetbrains.kotlin.config.KotlinSourceRootType
 import org.jetbrains.kotlin.idea.caches.PerModulePackageCacheService
+import org.jetbrains.kotlin.idea.roots.invalidateProjectRoots
 import org.jetbrains.kotlin.idea.util.rootManager
 import org.jetbrains.kotlin.idea.util.sourceRoot
 import org.jetbrains.kotlin.name.FqName
@@ -103,6 +104,7 @@ private fun Module.getOrConfigureKotlinSourceRoots(): List<VirtualFile> {
     return runWriteAction {
         val rootDir = rootManager.contentRoots.firstOrNull()
         rootDir?.createChildDirectory(project, "kotlin")
+        project.invalidateProjectRoots()
         getNonGeneratedKotlinSourceRoots()
     }
 }

idea/idea-core/src/org/jetbrains/kotlin/idea/roots/rootUtils.kt

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. 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.roots
+
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.roots.ex.ProjectRootManagerEx
+import com.intellij.openapi.util.EmptyRunnable
+
+fun Project.invalidateProjectRoots() {
+    ProjectRootManagerEx.getInstanceEx(this).makeRootsChange(EmptyRunnable.INSTANCE, false, true)
+}