[maruthang]

Fixes #5190. Also the root cause of swagger-api/swagger-ui#10418 (and the motivation behind the now-closed swagger-api/swagger-ui#10822, per @glowcloud's review there).

Problem

When an Example Object with only externalValue sits inside an externally referenced Path Item Object, dereferencing fails with:

ExampleElement value and externalValue fields are mutually exclusive.

The PathItemElement handler dereferences the external fragment with a nested visitor, then link.replaceWiths the merged Path Item — and the outer visitor descends into the already-dereferenced subtree. The nested pass has by then transcluded externalValue into value (annotating value with ref-origin meta) while intentionally keeping externalValue, so the outer pass re-visits an Example that now has both fields and trips the mutual-exclusion guard. Without the path-level $ref there is only one traversal, hence no error.

Fix

In the ExampleElement handlers of the 3.0, 3.1, and 3.2 dereference strategies, skip elements whose value carries the ref-origin meta (i.e. the value was already transcluded by a previous pass) before applying the mutual-exclusion check. A genuine violation (both value and externalValue in source) still errors as before.

Verification

• Reproduced the failure with the fixture from swagger-ui#10418 against @swagger-api/apidom-reference@1.11.3; with this guard applied the repro dereferences cleanly and the output is identical to the inline (no-$ref) equivalent.
• Added regression fixtures/tests external-value-path-item-ref to the example-object dereference suites for the 3.0 and 3.1 strategies.
• The full monorepo suite was not run locally (Windows machine constraints) — relying on CI for end-to-end validation.