public static ClickHouseBitmapValue ofEmpty(ClickHouseValue ref, ClickHouseDataType valueType) {
        ClickHouseBitmap v = ClickHouseBitmap.empty(valueType);
        return ref instanceof ClickHouseBitmapValue ? (ClickHouseBitmapValue) ((ClickHouseBitmapValue) ref).set(v)
                : new ClickHouseBitmapValue(v);
    }
Update given value to empty or create a new instance if {@code ref} is null.

@param ref       object to update, could be null
@param valueType value type, must be native integer
@return same object as {@code ref} or a new instance if it's null
clickhouse-data/src/main/java/com/clickhouse/data/value/ClickHouseBitmapValue.java