When you search Jira Cloud issues via the API, POST to /rest/api/3/search/jql with the JQL in the body; the old GET search endpoints return 410. Page with nextPageToken, not startAt, and stop when the token is missing. Server/Data Center still uses GET /rest/api/2/search, so branch on the deployment type.

Context: Jira API notes (statewave-connectors changelog): Atlassian removed GET /rest/api/2/search and /rest/api/3/search from Cloud (HTTP 410, CHANGE-2046). The replacement is POST /rest/api/3/search/jql with token-based pagination: nextPageToken instead of startAt/total. Pagination stops when the token is absent or a page is empty.