@Override
public Properties call() throws GitAPIException {
checkCallable();
GC gc = new GC((FileRepository) repo);
gc.setProgressMonitor(monitor);
if (this.expire != null)
gc.setExpire(expire);
try {
gc.gc();
return toProperties(gc.getStatistics());
} catch (IOException e) {
throw new JGitInternalException(JGitText.get().gcFailed, e);
} catch (ParseException e) {
throw new JGitInternalException(JGitText.get().gcFailed, e);
}