public FluentFuture<Integer> deleteAll() {
      checkState(numberToSkip == 0, "Cannot use .skip() with .deleteAll()");
      return repository.doDelete(criteria);
    }
Delete all matching documents from the collection if they matches {@link Criteria}.
@return future of number of deleted documents if WriteConcern allows.
mongo/src/org/immutables/mongo/repository/Repositories.java