docs: public void loadContentDefinition(final String entityId, final Command callback) {
  
          AsyncCallback<CmsContentDefinition> asyncCallback = new AsyncCallback<CmsContentDefinition>() {
  
              public void onFailure(Throwable caught) {
  
                  onRpcError(caught);
              }
  
              public void onSuccess(CmsContentDefinition result) {
  
                  registerContentDefinition(result);
                  callback.execute();
              }
          };
          getService().loadContentDefinition(entityId, asyncCallback);
      }