chore(sonar): fix code smell

Author: oliemansm

graphql-java-servlet/src/main/java/graphql/kickstart/servlet/BatchedQueryResponseWriter.java

@@ -27,7 +27,7 @@ public void write(HttpServletRequest request, HttpServletResponse response) thro
     // GiB of memory allocation during large response processing.
     List<byte[]> serializedResults = new ArrayList<>(2 * results.size() + 1);
 
-    if (results.size() > 0) {
+    if (!results.isEmpty()) {
       serializedResults.add("[".getBytes(StandardCharsets.UTF_8));
     } else {
       serializedResults.add("[]".getBytes(StandardCharsets.UTF_8));