Major Description
A good question came up on the mailing list recently regarding the re-use of the MessageCollector (http://mail-archives.apache.org/mod_mbox/samza-dev/201403.mbox/%3CCF3F4604.24550%25criccomini@linkedin.com%3E). This isn't the first time this question has been raised. It'd be good to document this both in the docs and the javadoc for the class itself (and in StreamTask).