Expand 'filter' javadoc.
Expand 'filter' javadoc.

chenrui2014/pollexor,hambroperks/pollexor,chenrui2014/pollexor,chenrui2014/pollexor,StevenTsai/pollexor,hambroperks/pollexor,qingsong-xu/pollexor,hambroperks/pollexor,qingsong-xu/pollexor,StevenTsai/pollexor,hambroperks/pollexor,square/pollexor,qingsong-xu/pollexor,square/pollexor,StevenTsai/pollexor