Add explicit default clauses to switches flagged by java/missing-case-in-switch

[vharseko]

Tier 3 of the warning-severity CodeQL triage (Tier 1 is #789, Tier 2 is #790). Closes all 38 java/missing-case-in-switch alerts.

What was wrong

All 38 flagged switch statements genuinely had no default: clause — that was verified for each one, not assumed. None of them is a bug today: for every enum value that is not listed, the correct behaviour is to do nothing and fall out of the switch, which is exactly what happens (falling through to a return false, to a shared return, or simply on to the next step).

The risk the rule points at is the future one: adding a value to ModificationType, SearchScope, Step, ServerStatus and friends would silently change behaviour at these 38 sites with nothing to flag it.

The change

Every flagged switch now ends with:

default:
  // No action needed for the remaining values.
  break;

The diff is additions only — no line is modified or removed, so no behaviour changes.

Explicit breaks

In Uninstaller, BindRule, BindOperationBasis, LocalBackendAddOperation and LocalBackendWorkflowElement the last case did not end with a break, which would have made the new default clause reachable by fall-through. The effect is identical, since the clause only breaks, but an explicit break; is added rather than leaving implicit fall-through behind.

Totals: 38 default: clauses, 38 comments, 43 break; (38 in the new clauses plus these 5).

Deliberately not touched

Five further switches in the same files have no default either, and are left alone because they are exhaustive — which is why CodeQL did not flag them:

Switch	Why it needs no default
Utils:199, LDAPConnection:361	PasswordPolicyWarningType has exactly two values, both covered
DirectoryServer:692	complete over SubSystem
AttrHistoricalSingle:290, AttrHistoricalMultiple:575	complete over HistKey

Adding default there would be noise, so the change is scoped precisely to the 38 alerts.

Verification

• mvn -o compile for opendj-ldap-toolkit and opendj-server-legacy — passes, with no fall-through warnings.
• Re-checked programmatically that each default landed inside its switch body: of the switches in the touched files, 80 now have a default and 5 do not — exactly the exhaustive ones listed above.

Note for reviewers

Three files are also touched by #790: BrowserController.java, SearchOperationBasis.java and UpgradeUtils.java. There is no overlap with #789. In UpgradeUtils the two edits are close together (try-with-resources around line 336 in #790, the default around line 360 here), and in all three files both branches add the same copyright line at the same place, so a small merge conflict is likely. Suggested order: #789 → #790 → this one.