public GroupFormat getGroupFormat() throws GuacamoleException {
        return environment.getProperty(CASGuacamoleProperties.CAS_GROUP_FORMAT, GroupFormat.PLAIN);
    }
Returns the format that CAS is expected to use for its group names, such
as {@link GroupFormat#PLAIN} (simple plain-text names) or
{@link GroupFormat#LDAP} (fully-qualified LDAP DNs). If not specified,
PLAIN is used by default.

@return
    The format that CAS is expected to use for its group names.

@throws GuacamoleException
    If the format specified within guacamole.properties is not valid.
extensions/guacamole-auth-sso/modules/guacamole-auth-sso-cas/src/main/java/org/apache/guacamole/auth/cas/conf/ConfigurationService.java