code: @Override
      public void execute(Environment env, Map params, TemplateModel[] loopVars, TemplateDirectiveBody body) throws TemplateException, IOException {
          if (params.size() > 1) {
              String message = "This directive doesn't allow multiple parameters.";
              errors.add(message);
              throw new TemplateModelException(message);
          }
          if (params.size() != 0 && !((Map.Entry)params.entrySet().toArray()[0]).getKey().equals("render"))
          {
              String message = "This directive only takes 'render'.";
              errors.add(message);
              throw new TemplateModelException(message);
          }
          Object renderParam = params.get("render");
          if (renderParam == null && params.size() != 0) return;
          if (params.size() == 0)
          {} else if (renderParam instanceof TemplateBooleanModel)
          {
              TemplateBooleanModel render = (TemplateBooleanModel) renderParam;
              if (BooleanUtils.isNotTrue(render.getAsBoolean()))
                  return;
          } else {
              String message = "This directive only accepts boolean values for 'render'.";
              errors.add(message);
              throw new TemplateModelException(message);
          }
          if (loopVars.length != 0) {
              String message = "This directive doesn't allow loop variables.";
              errors.add(message);
              throw new TemplateModelException(message);
          }
          WhereContext whereContext = (WhereContext)env.getCustomAttribute("whereTag");
          if (whereContext == null) {
              String message = "Can not find parent where clause.";
              errors.add(message);
              throw new TemplateModelException(message);
          }
          StringWriter stringWriter = new StringWriter();
          body.render(stringWriter);
          outputBody = stringWriter.toString();
          whereContext.addWhereClause(this);
      }
docs: Looks for a render option, to determine if it should be run. This is supposed to encapsulate a single SQL where
  clause. Such as "name IS NOT NULL" or "id > ${method.value(param.lowLimit)}". This should be encapsulated within
  a where tag. If this doesn't have an render attribute it will run regardless. When this is successful it will
  populate the parent where clause with the contents.
  
  {@inheritDoc}