Allow specifying custom `DateTimeFormatter` for `OffsetDateTime` ser/deser (new constructors?)

[ZIRAKrezovic]

Trying to make OffsetDateTime deserialize from ISO_LOCAL_DATE_TIME pattern by appending default offset of "0". This is easily doable with

    public static final DateTimeFormatter OFFSET_DATE_TIME_PARSER =
            new DateTimeFormatterBuilder()
                    .append(DateTimeFormatter.ISO_LOCAL_DATE_TIME)
                    .optionalStart()
                    .parseLenient()
                    .appendOffsetId()
                    .parseStrict()
                    .optionalEnd()
                    .parseDefaulting(ChronoField.OFFSET_SECONDS, 0)
                    .toFormatter();

        var parsed = OffsetDateTime.parse("2025-01-01T22:01:05", OFFSET_DATE_TIME_PARSER);

However, there is no easy way to override this parser, especially since InstantDeserializer.ISO_OFFSET_DATE_TIME is created with many parameters and calls methods that are private to the InstantDeserializer.

When looking at LocalDateTimeDeserializer it as a public constructor that accepts DateTimeFormatter as an arg.

Similar situation happens in OffsetDateTimeSerializer. I wish to only display 3 digits of nano-second instead of 9, but there's no right way to override DateTimeFormatter in OffsetDateTimeSerializer like there's in LocalDateTimeSerializer

Would you kindly support this use-case?

[cowtowncoder]

Adding accessible constructor sounds like a reasonable idea.

PRs welcome!

[cowtowncoder]

NOTE: depending on implementation, pr either here (2.x) or jackson-databind (3.x) -- since functionality embedded in databind for Jackson 3.

[cowtowncoder]

Ok: fixing via #379 by:

• Changing InstantDeserializer.withDateFormat(DTF) to be public
• Adding public OffsetDateTimeSerializer.withFormatter(DTF)

so that it is possible to construct customized instances: from unit tests:

InstantDeserializer<OffsetDateTime> customDeserializer =
    InstantDeserializer.OFFSET_DATE_TIME.withDateFormat(customFormatter);

OffsetDateTimeSerializer customSerializer =
    OffsetDateTimeSerializer.INSTANCE .withFormatter(dtf);

(note: did not change existing method name withDateFormat())

[cowtowncoder]

Fixed by #379.