Add when branches: remove unnecessary blank line

#KT-30426 Fixed

idea/src/org/jetbrains/kotlin/idea/quickfix/AddWhenRemainingBranchesFix.kt

@@ -19,6 +19,7 @@ package org.jetbrains.kotlin.idea.quickfix
 import com.intellij.codeInsight.intention.IntentionAction
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiWhiteSpace
 import org.jetbrains.kotlin.cfg.*
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
 import org.jetbrains.kotlin.descriptors.ClassKind
@@ -78,7 +79,7 @@ class AddWhenRemainingBranchesFix(
             val whenCloseBrace = element.closeBrace ?: throw AssertionError("isAvailable should check if close brace exist")
             val elseBranch = element.entries.find { it.isElse }
             val psiFactory = KtPsiFactory(element)
-
+            (whenCloseBrace.prevSibling as? PsiWhiteSpace)?.replace(psiFactory.createNewLine())
             for (case in missingCases) {
                 val branchConditionText = when (case) {
                     UnknownMissingCase, NullMissingCase, is BooleanMissingCase ->

idea/testData/quickfix/when/addRemainingBranchesBlankLine.kt

@@ -0,0 +1,11 @@
+// "Add remaining branches" "true"
+// WITH_RUNTIME
+
+sealed class A
+class B : A()
+
+fun test(a: A) {
+    val r = <caret>when (a) {
+
+    }
+}

idea/testData/quickfix/when/addRemainingBranchesBlankLine.kt.after

@@ -0,0 +1,11 @@
+// "Add remaining branches" "true"
+// WITH_RUNTIME
+
+sealed class A
+class B : A()
+
+fun test(a: A) {
+    val r = when (a) {
+        is B -> TODO()
+    }
+}

idea/testData/quickfix/when/addRemainingBranchesBlankLineWithComment.kt

@@ -0,0 +1,13 @@
+// "Add remaining branches" "true"
+// WITH_RUNTIME
+
+sealed class A
+class B : A()
+
+fun test(a: A) {
+    val r = <caret>when (a) {
+
+        // comment
+
+    }
+}

idea/testData/quickfix/when/addRemainingBranchesBlankLineWithComment.kt.after

@@ -0,0 +1,13 @@
+// "Add remaining branches" "true"
+// WITH_RUNTIME
+
+sealed class A
+class B : A()
+
+fun test(a: A) {
+    val r = when (a) {
+
+        // comment
+        is B -> TODO()
+    }
+}

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

@@ -13775,6 +13775,16 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
             runTest("idea/testData/quickfix/when/addElseBranchEnumStatement.kt");
         }
 
+        @TestMetadata("addRemainingBranchesBlankLine.kt")
+        public void testAddRemainingBranchesBlankLine() throws Exception {
+            runTest("idea/testData/quickfix/when/addRemainingBranchesBlankLine.kt");
+        }
+
+        @TestMetadata("addRemainingBranchesBlankLineWithComment.kt")
+        public void testAddRemainingBranchesBlankLineWithComment() throws Exception {
+            runTest("idea/testData/quickfix/when/addRemainingBranchesBlankLineWithComment.kt");
+        }
+
         @TestMetadata("addRemainingBranchesBoolean.kt")
         public void testAddRemainingBranchesBoolean() throws Exception {
             runTest("idea/testData/quickfix/when/addRemainingBranchesBoolean.kt");