presto-main/src/main/java/io/prestosql/type/ColorType.java/ColorType/getObjectValue
class ColorType:    @Override
    public Object getObjectValue(ConnectorSession session, Block block, int position)
    {
        if (block.isNull(position)) {
            return null;
        }

        int color = block.getInt(position, 0);
        if (color < 0) {
            return ColorFunctions.SystemColor.valueOf(-(color + 1)).getName();
        }

        return format("#%02x%02x%02x",
                (color >> 16) & 0xFF,
                (color >> 8) & 0xFF,
                color & 0xFF);
    }