Converter tests:

Change test data files extension to "java"

j2k/tests/testData/ast/callChainExpression/libraryMethodCall.java

@@ -0,0 +1,13 @@
+//file
+class Library {
+  static void call() {}
+
+  static String getString() { return ""; }
+}
+
+class User {
+  void main() {
+    Library.call();
+    Library.getString().isEmpty();
+  }
+}