Fix javac6 helper test

test/transform/resource/after-delombok/HelperInMethod.java

@@ -1,6 +1,6 @@
 public class HelperInMethod {
 	int someMethod(int arg1) {
-		int localVar = 5;
+		final int localVar = 5;
 
 		class Helpers {
 			int helperMethod(int arg) {

test/transform/resource/after-ecj/HelperInMethod.java

@@ -4,7 +4,7 @@ public class HelperInMethod {
     super();
   }
   int someMethod(int arg1) {
-    int localVar = 5;
+    final int localVar = 5;
     @Helper class Helpers {
       Helpers() {
         super();

test/transform/resource/before/HelperInMethod.java

@@ -2,7 +2,7 @@ import lombok.experimental.Helper;
 
 public class HelperInMethod {
 	int someMethod(int arg1) {
-		int localVar = 5;
+		final int localVar = 5;
 		
 		@Helper
 		class Helpers {