wrong datetime conversion when sending SmS

[junoyoon]

https://github.com/infobip/infobip-api-java-client/blob/f6889abeb4052e6077816f06e82fff909919fb99/src/main/java/com/infobip/JSON.java#L31C1-L32C71

this datetype is wrong for SMS.
For SMS, https://www.infobip.com/docs/api/channels/sms/outbound-sms/send-message/send-sms-messages
options > schedule > sendAt parameter require yyyy-MM-dd'T'HH:mm:ss.SSSZ
this ends with 'Z' and means UTC time.

but the DateTimeFormatter in SDK 'Z' means UTC but timezone offset (RFC 822) like +0900
This causes the imcompatibility b/w SDK and infobip api.

success

curl --request POST 'https://6zjqez.api.infobip.com/email/3/send' \
...
--form 'sendAt="2026-03-12T04:59:59.123Z"'

error

curl --request POST 'https://6zjqez.api.infobip.com/email/3/send' \
...
--form 'sendAt="2026-03-12T04:59:59.123+0000"'

To fix this,
the DateTimeFomatter in https://github.com/infobip/infobip-api-java-client/blob/f6889abeb4052e6077816f06e82fff909919fb99/src/main/java/com/infobip/JSON.java#L31C1-L32C71
should be

DateTimeFormatter f = DateTimeFormatter
        .ofPattern("yyyy-MM-dd'T'HH:mm:ss.SSSX")
        .withZone(ZoneOffset.UTC); 

[dnumicmesa]

Hi @junoyoon ,

first of all, thank you for using our library.

Regarding the issue you experienced, we noticed that you used Email V3 endpoint, which we checked and can confirm that it is only supporting format with 'Z' at the end. We checked if such issue is happening with SMS, but we got successful responses with both formats. Email V3 issue will be resolved (API aligned with SMS) on API directly (so no need to issue SDK patch update) in few weeks time.

I will close this ticket when issue is resolved on our end, and then you can confirm if it is working as expected from your side.