Surround with braces when completing backing field in string template

idea/src/org/jetbrains/kotlin/idea/completion/LookupElementsCollector.kt

@@ -118,9 +118,12 @@ class LookupElementsCollector(
         }
 
         if (descriptor is PropertyDescriptor) {
-            val lookupElement = lookupElementFactory.createBackingFieldLookupElement(descriptor, inDescriptor, resolutionFacade)
+            var lookupElement = lookupElementFactory.createBackingFieldLookupElement(descriptor, inDescriptor, resolutionFacade)
             if (lookupElement != null) {
-                addElement(lookupElement)
+                if (surroundCallsWithBraces) {
+                    lookupElement = lookupElement!!.withBracesSurrounding()
+                }
+                addElement(lookupElement!!)
             }
         }
     }

idea/testData/completion/handlers/basic/stringTemplate/BackingField.kt

@@ -0,0 +1,10 @@
+class C {
+    var property = "abc"
+        get() = $property + 1
+
+    fun foo(){
+        "$<caret>"
+    }
+}
+
+// ELEMENT: $property

idea/testData/completion/handlers/basic/stringTemplate/BackingField.kt.after

@@ -0,0 +1,10 @@
+class C {
+    var property = "abc"
+        get() = $property + 1
+
+    fun foo(){
+        "${$property<caret>}"
+    }
+}
+
+// ELEMENT: $property

idea/tests/org/jetbrains/kotlin/completion/handlers/BasicCompletionHandlerTestGenerated.java

@@ -113,6 +113,12 @@ public class BasicCompletionHandlerTestGenerated extends AbstractBasicCompletion
             JetTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/completion/handlers/basic/stringTemplate"), Pattern.compile("^(.+)\\.kt$"), true);
         }
 
+        @TestMetadata("BackingField.kt")
+        public void testBackingField() throws Exception {
+            String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/handlers/basic/stringTemplate/BackingField.kt");
+            doTest(fileName);
+        }
+
         @TestMetadata("NotEmptyPrefix.kt")
         public void testNotEmptyPrefix() throws Exception {
             String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/handlers/basic/stringTemplate/NotEmptyPrefix.kt");