MariaDB Connector/J introduced new DATETIME implementation in version 1.3.0 which breaks legacy code even though useLegacyDatetimeCode is set to true. Before, we have used version 1.1.8 in the following manner (simplified):

Calendar calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));

statement.setTimestamp(index, timestamp, calendar);

Thus, we instructed to always use UTC regardless of the server/client TimeZone. After upgrading to the version 1.4.2 the above-mentioned code stopped working even with useLegacyDatetimeCode set to true. This is rather obvious if we take a look at TimestampParameter source code:

public void writeBinary(PacketOutputStream writeBuffer) {

    if (options.useLegacyDatetimeCode) {

        calendar = Calendar.getInstance();

    }

    calendar.setTimeInMillis(ts.getTime());

    writeBuffer.writeTimestampLength(calendar, ts);

}

As you can see, this code completely disregards calendar passed to it as a parameter (it saved in the constructor). As I see it, it is a breaking change.

If I set useLegacyDatetimeCode to false it will use server's time zone, which also is not a behavior we are trying to achieve.