While I was going through the JDBC Adapter source code, I noticed a Calendar was required to create the Arrow Schema (for any Timestamp fields), and also needed for converting a JDBC ResultSet to an ArrowVector (for Date, Time, and Timestamp fields).
However, Arrow Timestamps do not require a time zone, and none of the JDBC getters for Date, Time, and Timestamp require a Calendar.
I am proposing a change to make the Schema creator and ResultSet converter support null Calendars. If a Calendar is available, it will be used, and if not, it will not be used.
The existing SureFire plugin configuration uses a UTC calendar for the database, which is the default Calendar in the existing code. Likewise, no changes to the unit tests are required to provide adequate coverage for the change.