Converter tests:

Change test data files extension to "java"

j2k/tests/testData/ast/rawGenerics/kt-540.java

@@ -0,0 +1,13 @@
+//file
+package demo;
+
+import java.util.List;
+import java.util.LinkedList;
+
+class Test {
+  void main() {
+    List<String> common = new LinkedList<String>();
+    List raw = new LinkedList<String>();
+    List superRaw = new LinkedList();
+  }
+}