fix size() call in template
fix size() call in template

aglne/lenskit,vaibhav345/lenskit,kluver/lenskit,tajinder-txstate/lenskit,amaliujia/lenskit,vijayvani/Lenskit,kluver/lenskit,tajinder-txstate/lenskit,chrysalag/lenskit,martinlaz/lenskit,kluver/lenskit,kluver/lenskit,vaibhav345/lenskit,binweiwu/lenskit,vijayvani/Lenskit,amaliujia/lenskit,martinlaz/lenskit,chrysalag/lenskit,kluver/lenskit,aglne/lenskit,tajinder-txstate/lenskit,vaibhav345/lenskit,blankazucenalg/lenskit,binweiwu/lenskit,linjunleo/lenskit,tajinder-txstate/lenskit,vaibhav345/lenskit,blankazucenalg/lenskit,linjunleo/lenskit