code: @Override
      public String getLayoutContentByAppId(String appId) {
          String value = propertyService.getValue(PROPERTY_LAYOUT_ASSOCIATION, appId);
          return value == null ? null : getLayoutContent(new LayoutIdentifier(value, true));
      }
docs: Load the layout associated with the specified application id.
  
  @param appId An application id.
  @return The layout content.