Haw. Rev. Stat. § 490:2A-202: Final expression: parol or extrinsic evidence.

Terms with respect to which the confirmatory memoranda of the parties agree or which are otherwise set forth in a record intended by the parties as a final expression of their agreement with respect to the terms as are included therein shall not be contradicted by evidence of any prior agreement or of a contemporaneous oral agreement but may be explained or supplemented by:

(1) Course of dealing or usage of trade or by course of performance; and

(2) Evidence of consistent additional terms unless the court finds the record to have been intended also as a complete and exclusive statement of the terms of the agreement.