CONCLUSIVENESS OF DETERMINATIONS AND DECISIONS.

Except insofar as reconsideration of any determination is had under Section 2-506 of this title, any right, fact, or matter in issue, directly passed upon or necessarily involved in a determination or redetermination which has become final, or in a decision on appeal under this subsection which has become final, shall be conclusive for all the purposes of this act as between the Commission, the claimant, and all employers who had notice of such determination, redetermination, or decision. Subject to appeal proceedings and judicial review as provided in this title, any determination, redetermination or decision as to rights to benefits shall be conclusive for all the purposes of this act and shall not be subject to collateral attack by any party.