New J2K: add multi-file conversion tests from old j2k

nj2k/testData/multiFile/GetterAndSetterUsages/2.java

@@ -0,0 +1,14 @@
+package test;
+
+public class B {
+    void foo(AAA a) {
+        a.setX(a.getX() + 1);
+        y += "a";
+    }
+
+    private String y = "";
+
+    public String getYY() {
+        return y;
+    }
+}