code: private Map<String, Object> getContentForNav(Map<String, Object> document) {
          Map<String, Object> navDocument = new HashMap<>();
          navDocument.put(Attributes.NO_EXTENSION_URI, document.get(Attributes.NO_EXTENSION_URI));
          navDocument.put(Attributes.URI, document.get(Attributes.URI));
          navDocument.put(Attributes.TITLE, document.get(Attributes.TITLE));
          return navDocument;
      }
docs: Creates a simple content model to use in individual post navigations.
  
  @param document
  @return