Switch off inspections on Kotlin files not in project source

To switch them off, KotlinDefaultHighlightingSettingsProvider
was introduced.
So #KT-19377 Fixed

idea/src/META-INF/plugin.xml

@@ -480,6 +480,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/META-INF/plugin.xml.172

@@ -481,6 +481,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/META-INF/plugin.xml.173

@@ -481,6 +481,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/META-INF/plugin.xml.182

@@ -482,6 +482,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/META-INF/plugin.xml.as31

@@ -481,6 +481,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/META-INF/plugin.xml.as32

@@ -481,6 +481,8 @@ The Kotlin plugin provides language support in IntelliJ IDEA and Android Studio.
 
     <codeInsight.linkHandler prefix="#kotlinClass/" handlerClass="org.jetbrains.kotlin.idea.highlighter.markers.KotlinClassTooltipLinkHandler"/>
 
+    <defaultHighlightingSettingProvider language="kotlin" implementation="org.jetbrains.kotlin.idea.highlighter.KotlinDefaultHighlightingSettingsProvider"/>
+
     <typeDeclarationProvider implementation="org.jetbrains.kotlin.idea.codeInsight.KotlinTypeDeclarationProvider"/>
 
     <completion.contributor language="kotlin"

idea/src/org/jetbrains/kotlin/idea/highlighter/KotlinDefaultHighlightingSettingsProvider.kt

@@ -0,0 +1,21 @@
+/*
+ * 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.highlighter
+
+import com.intellij.codeInsight.daemon.impl.analysis.DefaultHighlightingSettingProvider
+import com.intellij.codeInsight.daemon.impl.analysis.FileHighlightingSetting
+import com.intellij.openapi.project.Project
+import com.intellij.openapi.vfs.VirtualFile
+import org.jetbrains.kotlin.idea.util.ProjectRootsUtil
+
+class KotlinDefaultHighlightingSettingsProvider : DefaultHighlightingSettingProvider() {
+    override fun getDefaultSetting(project: Project, file: VirtualFile): FileHighlightingSetting? {
+        return when {
+            ProjectRootsUtil.isProjectSourceFile(project, file) -> null
+            else -> FileHighlightingSetting.SKIP_INSPECTION
+        }
+    }
+}