How to use Groups.startsWith expression in SAML Attribute Statements?

Hello! I'm trying to create an Expression Language statement that would fetch the user's groups using a startsWith query, and then extract some strings from the group names (they have a specific name format). My EL statement works fine for Oauth claims, but I can't get it to work as a SAML Attribute Statement. My questions is, does the SAML Attribute Statement support Groups.startsWith, Groups.contains or Groups.endsWith? It works when I use isMemberOfGroupName or getFilteredGroups, but these functions won't do the query I need.