Make CTabFolder.setItemOrder package-private again, keep moveItem

[vogella]

Following review feedback on #3350, CTabFolder.setItemOrder(int[]) should not be exposed as public API. This demotes it back to a package-private helper and drops its @since tag, while keeping the public moveItem(int, int) method as the supported primitive for the common single-tab reorder (drag) gesture.

The priority[]/firstIndex remap fix from #3350 is retained, since moveItem delegates to setItemOrder and relies on it to keep the chevron and scroll state correct after a reorder. The unit tests that called setItemOrder directly are removed (they can no longer compile from the test package); the moveItem tests stay and continue to exercise the remap logic.

[github-actions]

Test Results

  182 files  ± 0    182 suites  ±0   27m 37s ⏱️ +54s
4 729 tests  -  5  4 706 ✅  -  5   23 💤 ±0  0 ❌ ±0 
6 848 runs   - 30  6 685 ✅  - 30  163 💤 ±0  0 ❌ ±0 

Results for commit 12b780e. ± Comparison against base commit 42b9859.

This pull request removes 5 tests.

org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder ‑ test_setItemOrder_chevronStillWorks
org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder ‑ test_setItemOrder_errorCases
org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder ‑ test_setItemOrder_identityIsNoOp
org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder ‑ test_setItemOrder_keepsSelection
org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder ‑ test_setItemOrder_reordersItems

[vogella]

The removed tests are due to the removal of the API. The fix in the incorrect handling of reordering in setItemOrder is of course left in the code and is indirectly tested via the moveItem method.

FYI - @HeikoKlare I plan to merge this today, to avoid having a SWT release with unwanted API.

[HeikoKlare]

The removed tests are due to the removal of the API.

Would it make sense to preserve the tests as unit tests instead of API tests?

[vogella]

The removed tests are due to the removal of the API.

Would it make sense to preserve the tests as unit tests instead of API tests?

I would say no, we didn't have them before and the new moveItem API is well-tested.