Add 'Incorrect Transient' diagnostic

when users write @Transient, they get @kotlin.jvm.Transient, because it's always in auto-import.
This annotation does not work with @Serializable classes; @kotlinx.serialization.Transient should be used instead.

Add quickfix for 'incorrect transient' diagnostic:
'Import kotlinx.serialization.Transient'

plugins/kotlin-serialization/kotlin-serialization-ide/build.gradle.kts

@@ -15,6 +15,9 @@ dependencies {
     compile(project(":idea:idea-maven"))
     compile(project(":plugins:annotation-based-compiler-plugins-ide-support"))
     compileOnly(intellijDep())
+    Platform[192].orHigher {
+        compileOnly(intellijPluginDep("java"))
+    }
     excludeInAndroidStudio(rootProject) { compileOnly(intellijPluginDep("maven")) }
     compileOnly(intellijPluginDep("gradle"))
 
@@ -30,5 +33,5 @@ sourceSets {
 runtimeJar()
 
 projectTest(parallel = true) {
-    
+
 }

plugins/kotlin-serialization/kotlin-serialization-ide/src/org/jetbrains/kotlinx/serialization/idea/quickfixes/IncorrectTransientQuickFix.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2010-2020 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.kotlinx.serialization.idea.quickfixes
+
+import com.intellij.codeInsight.intention.IntentionAction
+import com.intellij.openapi.editor.Editor
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiElement
+import org.jetbrains.kotlin.diagnostics.Diagnostic
+import org.jetbrains.kotlin.idea.quickfix.KotlinQuickFixAction
+import org.jetbrains.kotlin.idea.quickfix.KotlinSingleIntentionActionFactory
+import org.jetbrains.kotlin.idea.util.ImportInsertHelperImpl
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlinx.serialization.compiler.diagnostic.SerializationErrors
+import org.jetbrains.kotlinx.serialization.compiler.resolve.SerializationAnnotations
+
+internal class AddKotlinxSerializationTransientImportQuickFix(expression: PsiElement) :
+    KotlinQuickFixAction<PsiElement>(expression) {
+    override fun invoke(project: Project, editor: Editor?, file: KtFile) {
+        // Do not use Helper itself because it does not insert import on conflict;
+        // so it will always fail because k.jvm.Transient is always in auto-import
+        ImportInsertHelperImpl.addImport(project, file, SerializationAnnotations.serialTransientFqName, allUnder = false)
+    }
+
+    override fun getFamilyName(): String = text
+
+    override fun getText(): String = "Import ${SerializationAnnotations.serialTransientFqName}"
+
+    object Factory : KotlinSingleIntentionActionFactory() {
+        override fun createAction(diagnostic: Diagnostic): IntentionAction? {
+            if (diagnostic.factory != SerializationErrors.INCORRECT_TRANSIENT) return null
+            val castedDiagnostic = SerializationErrors.INCORRECT_TRANSIENT.cast(diagnostic)
+
+            val element = castedDiagnostic.psiElement
+
+            return AddKotlinxSerializationTransientImportQuickFix(element)
+        }
+    }
+}

plugins/kotlin-serialization/kotlin-serialization-ide/src/org/jetbrains/kotlinx/serialization/idea/quickfixes/SerializationQuickFixContributor.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2020 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.kotlinx.serialization.idea.quickfixes
+
+import org.jetbrains.kotlin.idea.quickfix.QuickFixContributor
+import org.jetbrains.kotlin.idea.quickfix.QuickFixes
+import org.jetbrains.kotlinx.serialization.compiler.diagnostic.SerializationErrors
+
+class SerializationQuickFixContributor : QuickFixContributor {
+    override fun registerQuickFixes(quickFixes: QuickFixes) {
+        quickFixes.register(SerializationErrors.INCORRECT_TRANSIENT, AddKotlinxSerializationTransientImportQuickFix.Factory)
+    }
+}