code: public Record removeNullValueColumns() {
  		for (java.util.Iterator<Entry<String, Object>> it = getColumns().entrySet().iterator(); it.hasNext();) {
  			Entry<String, Object> e = it.next();
  			if (e.getValue() == null) {
  				it.remove();
  			}
  		}
  		return this;
  	}
docs: Remove columns if it is null.