Where the defendant fails or refuses to perform his contract and is justified therein by the plaintiff's own breach of duty or non-performance of a condition, but the plaintiff has rendered a part performance under the contract that is a net benefit to the defendant, the plaintiff can get judgment for the amount of such benefit...if [] the defendant, with knowledge that the plaintiffs breach of duty of duty or non-performance of condition has occurred...assents to the rendition of the part performance, or accepts the benefit of it, or retains property received although its return in specie is still not unreasonably difficult or injurious.Power-Matics, Inc. v. Ligotti, 79 N.J. Super. 294, 306-07 (App. Div. 1963) (citing 2 Restatement, Contracts, ยง 357, p. 623). See also Kutzin v. Pimie, 124 N.J. 500, 515-516 (N.J. 1991).