code: protected final <T> T __getRenderPropertyAs(String name, T def) {
          Object o = __getRenderProperty(name, def);
          return null == o ? def : (T) o;
      }
docs: Get render property by name and do type cast to the specified default value.
  If the render property cannot be found by name, then return the default value
  
  @param name
  @param def
  @param <T>
  @return a render property
  @see #__getRenderProperty(String)