[#19921] Add RFC 3339 compatible Jackson module for java.time types

[beikov]

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@bbdouglas (2017/07) @sreeshas (2017/08) @jfiala (2017/08) @lukoyanov (2017/09) @cbornet (2017/09) @jeff9finger (2018/01) @karismann (2019/03) @Zomzog (2019/04) @lwlee2608 (2019/10) @martin-mfg (2023/08)

[cbornet]

I'm pretty sure Java implementations can already deserialize RFC3339 datetimes...

[cbornet]

The JavaTimeModule can already deserialize RFC3339 datetimes

[beikov]

I'm pretty sure Java implementations can already deserialize RFC3339 datetimes...

I can tell you, it does not. The JavaTime module uses com.fasterxml.jackson.datatype.jsr310.deser.InstantDeserializer for Instant, ZonedDateTime and OffsetDateTime types. This in turn, uses the DateTimeFormatter.ISO_INSTANT, DateTimeFormatter.ISO_OFFSET_DATE_TIME and DateTimeFormatter.ISO_ZONED_DATE_TIME formats respectively for parsing.
You can look into the javadocs of DateTimeFormatter and easily figure out that it implements ISO8601 which has T as the only valid separator between date and time, whereas RFC3339 also allows a space character.

If you don't believe me, try it out for yourself: https://onecompiler.com/jshell/42vrgfpy8

[cbornet]

As per its ABNF, RFC3339 doesn't support space as a separator.
But it's true that there's a note that says applications may choose to use space... I wouldn't recommend to use it though...
So maybe we could be lenient on deser and accept it 🤔
Do people really use RFC3339 with space separator ?

[beikov]

I integrated an application which uses this format, so clearly, there is precedent for this need. I doubt that application will change the representation.
I can't speak for other users, but if OpenAPI claims that RFC3339 format is supported, then the OpenAPI generator should respect that.

[martin-mfg]

Hi @beikov, thanks for the PR! Apart from the small topics I commented on separately, this PR looks good to me. I tested the changes locally and can confirm that the changes enable the parsing of additional timestamp formats.

[martin-mfg]

please see #19925 (comment) and #19925 (comment)