IDEA-143911 (quick fix produces uncompilable code (StringBuffer can be replaced with String))

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/style/StringBufferReplaceableByStringInspection.java

@@ -209,7 +209,7 @@ public class StringBufferReplaceableByStringInspection extends BaseInspection {
       }
 
       if (element instanceof PsiWhiteSpace) {
-        if (element.getText().contains("\n")) {
+        if (element.getText().contains("\n") && result.length() > 0) {
           result.append('\n'); // keep line break structure
         }
       }

plugins/InspectionGadgets/test/com/siyeh/igfixes/style/replace_with_string/Linebreaks.after.java

@@ -0,0 +1,9 @@
+class Linebreaks {
+
+  void m(String code) {
+    String controlDigit = String.valueOf(code.charAt(5)) +
+            code.charAt(7) +
+            code.charAt(9) +
+            code.charAt(11);
+  }
+}

plugins/InspectionGadgets/test/com/siyeh/igfixes/style/replace_with_string/Linebreaks.java

@@ -0,0 +1,10 @@
+class Linebreaks {
+
+  void m(String code) {
+    String controlDigit = new Stri<caret>ngBuilder()
+      .append(code.charAt(5))
+      .append(code.charAt(7))
+      .append(code.charAt(9))
+      .append(code.charAt(11)).toString();
+  }
+}

plugins/InspectionGadgets/testsrc/com/siyeh/ig/fixes/style/StringBufferReplaceableByStringFixTest.java

@@ -35,4 +35,5 @@ public class StringBufferReplaceableByStringFixTest extends IGQuickFixesTestCase
   public void testMethodCallOnString() { doTest(InspectionGadgetsBundle.message("string.builder.replaceable.by.string.quickfix")); }
   public void testComplex1() { doTest(InspectionGadgetsBundle.message("string.builder.replaceable.by.string.quickfix")); }
   public void testComplex2() { doTest(InspectionGadgetsBundle.message("string.builder.replaceable.by.string.quickfix")); }
+  public void testLinebreaks() { doTest(InspectionGadgetsBundle.message("string.builder.replaceable.by.string.quickfix")); }
 }