code: protected final <T> T __getRenderProperty(String name, T def) {
          Object o = __renderArgs.get(name);
          return (T) (__isDefVal(o) ? def : o);
      }
docs: Get render property by name. And do type case by the left value of the expression.
  <p/>
  <p>If no property found by name then return the default value specified</p>
  
  @param name
  @param def
  @param <T>
  @return a render property