HelloWorldServlet: Open Writer in try-with-resource

Change-Id: I057fea5f3a47c5cb7dd8c9253de601634b679ccc
diff --git a/src/main/java/com/googlesource/gerrit/plugins/cookbook/HelloWorldServlet.java b/src/main/java/com/googlesource/gerrit/plugins/cookbook/HelloWorldServlet.java
index d2c3935..b1493c2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/cookbook/HelloWorldServlet.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/cookbook/HelloWorldServlet.java
@@ -46,12 +46,12 @@
       final HttpServletResponse rsp) throws IOException, ServletException {
     rsp.setContentType("text/html");
     rsp.setCharacterEncoding("UTF-8");
-    final Writer out = rsp.getWriter();
-    out.write("<html>");
-    out.write("<body>");
-    out.write("<h2>Hello world!</h2>");
-    out.write("</body>");
-    out.write("</html>");
-    out.close();
+    try (Writer out = rsp.getWriter()) {
+      out.write("<html>");
+      out.write("<body>");
+      out.write("<h2>Hello world!</h2>");
+      out.write("</body>");
+      out.write("</html>");
+    }
   }
 }