This future completes successfully once the underlying entity stream has been successfully drained (and fails otherwise).
This future completes successfully once the underlying entity stream has been successfully drained (and fails otherwise).
This future completes successfully once the underlying entity stream has been successfully drained (and fails otherwise).
This future completes successfully once the underlying entity stream has been successfully drained (and fails otherwise).
Represents the currently being-drained HTTP Entity which triggers completion of the contained Future once the entity has been drained for the given HttpMessage completely.