/**
  * Return true if the given Doc should be included in the serialized form.
  *
  * @param doc the Doc object to check for serializability.
  */
 public static boolean serialInclude(Doc doc) {
   if (doc == null) {
     return false;
   }
   return doc.isClass() ? serialClassInclude((ClassDoc) doc) : serialDocInclude(doc);
 }