Adding more comments for FlashMap.java

Comment From: pivotal-cla

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Comment From: pivotal-cla

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Comment From: bclozel

Thanks for your first contribution but I believe this comment is misleading. This is not setting an expiration delay (as in number of seconds until expiration), but actually an Epoch time (as in System.currentTimeMillis()).

As a result I don't think this change is valid.

Comment From: lamtrinhdev

Dear @bclozel ,

Thank you for your feedback, @bclozel . You are right, let me close this PR.

Thanks, Lam