Since Thymeleaf 2.1 you can do this:
<a data-th-attr="data-groupid=${somevalue}, data-groupname=${someothervalue}">...</a>
source
Since Thymeleaf 2.1 you can do this:
<a data-th-attr="data-groupid=${somevalue}, data-groupname=${someothervalue}">...</a>
source