Converter tests:

Change test data files extension to "java"

j2k/tests/testData/ast/issues/kt-824-isDir.java

@@ -0,0 +1,19 @@
+//file
+package test;
+import java.io.File;
+
+/**
+ * User: ignatov
+ */
+public class Test {
+    public static boolean isDir(File parent) {
+        if (parent == null || !parent.exists()) {
+            return false;
+        }
+        boolean result = true;
+        if (parent.isDirectory()) {
+            return true;
+        } else
+            return false;
+    }
+}