Fix #1407 (@JsonFormat.pattern is ignored for java.sql.Date valued properties)

[sangpire]

Here is the fix for #1407

[cowtowncoder]

First of all, thank you for the PR!

Quick question does this still default to using the odd format that java.sql.Date.toString() provides? While odd, that should still happen for backwards compatibility reasons, in my opinion.

[sangpire]

No.

Default to use the StdDateFormat.DATE_FORMAT_STR_ISO8601 Pattern.

The comment means that before changes,
A SqlDateSerializer instance's customFormat value are always null.
So values are serialized by java.sql.Date.toString() like the yyyy-MM-dd pattern.

If I create a test with the yyyy-MM-dd pattern like others,
that will pass without changes.

So I use the yyyy.MM.dd patters.

[cowtowncoder]

@sangpire This would then be breaking change, and I don't think that is warranted. If we were starting from scratch I would agree with the change, but as things are not so much.

So: I would like behavior when there is no custom pattern specified to be the same as with 2.8.

[sangpire]

Thank you for finishing.