Hi team , I am interacting with JIRA through its REST API v2
and there are some unexpected behaviors compare to official developer document
JIRA software version: 8.8.1

Cases:
- About developer REST API reference:
I found 2 REST API references: Jira Server platform REST API reference(Jira 8.8.1) vs Jira Cloud platform Developer REST API v2 Reference.
Both of these references support the “/rest/api/2”, and I compared these 2 references, some APIs in Jira Server platform REST API reference are missing in the Jira Cloud platform Developer REST API v2 Reference, would you please show me which reference should I follow for this Jira software v8.8.1?
- Unable to set an assignee while creating an Jira issue
According to the example in creating an issue in both references, there is an field “assignee” in the Body Parameters with user’s account id / name. I think the ‘Create Issue’ REST API mentions in both references should support creating an issue with “assignee” which is offered in the request body.
Example in Jira Cloud platform Developer REST API v2 Reference

Create issue and provide assignee with accountId
Example in Jira Server platform REST API reference(Jira 8.8.1)

Create issue and provide assignee with name
However, I encounter 2 issues in creating an issue with “assignee”:
- I try to set the assignee with name and key, but after creating issue successfully, the assignee is not as expected (it has been assigned as the basic-auth user who post the request)
- I try to set it with the accountId, however, no “accountId” in the response: please check this screenshot

Right now when I want to create an issue with “assignee”, I have to call 2 APIs:
- Create an issue without “assignee” first;
- Update the “assignee” field on the issue I just created
This make me worry that, I am not sure whether some other fields would cause the same issue as the field “assignee” does in creating an issue. If yes, then it would be a very bad user experience.
- Unable to retrieve values on custom field according REST API reference
Again, while I am trying to creating an issue, I would like to retrieve values from my custom field under project which user selected.
I try the REST API mentions in both references, but the result is not expected, would you please advise me how to retrieve the options/value from my customField?
Here are the details:
- In Jira Server platform REST API reference(Jira 8.8.1),
There isn’t any REST API to list the options by customFieldId, only has an Get custom field option API to get the option with specific option id (GET /rest/api/2/customFieldOption/{id})
- In Jira Cloud platform Developer REST API v2 Reference, It do provide an REST Get custom field options (context) API to retrieve the options by customFieldId an contextId (GET /rest/api/3/field/{fieldId}/context)
Unfortunately, it response 404 when I try to lookup contextId by customFieldId.
Here are the steps:
Response:
Get ContextId by customFeildId: https://gbm-bds-jira.systems.uk.hsbc:8443/rest/api/2/field/customfield_10200/context
Response:
