KT-20880: Fix AddDocumentationFix to add multiline comment

#KT-20880 fixed

idea/idea-analysis/src/org/jetbrains/kotlin/idea/kdoc/KDocMissingDocumentationInspection.kt

@@ -23,15 +23,20 @@ import com.intellij.codeInspection.ProblemsHolder
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiElementVisitor
+import com.intellij.psi.impl.source.PostprocessReformattingAspect
 import org.jetbrains.kotlin.descriptors.CallableMemberDescriptor
 import org.jetbrains.kotlin.descriptors.MemberDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
+import org.jetbrains.kotlin.idea.core.unblockDocument
 import org.jetbrains.kotlin.idea.inspections.AbstractKotlinInspection
 import org.jetbrains.kotlin.idea.inspections.findExistingEditor
+import org.jetbrains.kotlin.kdoc.psi.impl.KDocSection
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtPsiFactory
+import org.jetbrains.kotlin.psi.psiUtil.endOffset
+import org.jetbrains.kotlin.psi.psiUtil.getChildOfType
 import org.jetbrains.kotlin.psi.psiUtil.getParentOfType
-import org.jetbrains.kotlin.psi.psiUtil.startOffset
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 import org.jetbrains.kotlin.resolve.source.getPsi
 
@@ -66,9 +71,27 @@ class KDocMissingDocumentationInspection(): AbstractKotlinInspection() {
             if (!FileModificationService.getInstance().preparePsiElementForWrite(descriptor.psiElement)) return
             val declaration = descriptor.psiElement.getParentOfType<KtNamedDeclaration>(true)
                               ?: throw IllegalStateException("Can't find declaration")
-            declaration.addBefore(KDocElementFactory(project).createKDocFromText("/**  */"), declaration.firstChild)
+
-            val editor = descriptor.psiElement.findExistingEditor()
+
-            editor?.caretModel?.moveToOffset(declaration.startOffset + 4)
+            declaration.addBefore(KDocElementFactory(project).createKDocFromText("/**\n*\n*/\n"), declaration.firstChild)
+
+            val editor = descriptor.psiElement.findExistingEditor() ?: return
+
+
+            // If we just add whitespace
+            // /**
+            //  *[HERE]
+            // it will be erased by formatter, so following code adds it right way and moves caret then
+            editor.unblockDocument()
+
+            val section = declaration.firstChild.getChildOfType<KDocSection>() ?: return
+            val asterisk = section.firstChild
+
+            PostprocessReformattingAspect.getInstance(project).disablePostprocessFormattingInside {
+                val whitespace = KtPsiFactory(project).createWhiteSpace()
+                section.addAfter(whitespace, asterisk)
+                editor.caretModel.moveToOffset(asterisk.endOffset + 1)
+            }
         }
     }
 }

idea/testData/quickfix/kdocMissingDocumentation/simple.kt.after

@@ -1,5 +1,7 @@
 // "Add documentation" "true"
 
-/** <caret> */
+/**
+ * <caret>
+ */
 class C {
 }

idea/testData/quickfix/kdocMissingDocumentation/withIndentation.kt

@@ -0,0 +1,9 @@
+// "Add documentation" "true"
+
+
+class C {
+
+    fun <caret>foo() {
+
+    }
+}

idea/testData/quickfix/kdocMissingDocumentation/withIndentation.kt.after

@@ -0,0 +1,12 @@
+// "Add documentation" "true"
+
+
+class C {
+
+    /**
+     * <caret>
+     */
+    fun foo() {
+
+    }
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -6781,6 +6781,12 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/kdocMissingDocumentation/simple.kt");
             doTest(fileName);
         }
+
+        @TestMetadata("withIndentation.kt")
+        public void testWithIndentation() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/quickfix/kdocMissingDocumentation/withIndentation.kt");
+            doTest(fileName);
+        }
     }
 
     @TestMetadata("idea/testData/quickfix/lateinit")