code: public static OverwritePolicy byDateTo(String attribute, Calendar end) {
  		return new DateRangeOverwritePolicy(attribute, null, end);
  	}
docs: Returns an {@link OverwritePolicy} that deletes records with a date
  before or on the given date in the specified column.
  <p>
  Records with an empty date value in existing data are also deleted.
  
  @param attribute date attribute to compare
  @param end last day (inclusive) up to which to delete data
  @return {@link OverwritePolicy} object