For each operator in Thymeleaf

Use th:block as stated in the Thymeleaf guide

th:block is a mere attribute container that allows template developers to specify whichever attributes they want. Thymeleaf will execute these attributes and then simply make the block disappear without a trace.

So it could be useful, for example, when creating iterated tables that require more than one <tr> for each element:

<table>
   <th:block th:each="user : ${users}">
      <tr>
         <td th:text="${user.login}">...</td>
         <td th:text="${user.name}">...</td>
      </tr>
      <tr>
         <td colspan="2" th:text="${user.address}">...</td>
      </tr>
   </th:block>
</table>