Refactor to use String.isEmpty

Author: miasma

commonmark/src/main/java/org/commonmark/renderer/text/CoreTextContentNodeRenderer.java

@@ -236,7 +236,7 @@ private void writeText(String text) {
     private void writeLink(Node node, String title, String destination) {
         boolean hasChild = node.getFirstChild() != null;
         boolean hasTitle = title != null && !title.equals(destination);
-        boolean hasDestination = destination != null && !destination.equals("");
+        boolean hasDestination = destination != null && !destination.isEmpty();
 
         if (hasChild) {
             textContent.write('"');