Hi,
A beta version of Collapsed Topics for Moodle 2.5 beta is available from https://moodle.org/plugins/pluginversion.php?id=2544.
Please note that this is 'beta' and must not be used on production servers. The code will remain in a 'beta' state until 2.5 itself becomes 'stable' and any future issues have been corrected.
Cheers,
Gareth