2089. The parties may stipulate in writing and in express terms that, even after the termination of the contract, the employee may neither compete with his employer nor participate in any capacity whatsoever in an enterprise which would then compete with him.
Such a stipulation shall be limited, however, as to time, place and type of employment, to whatever is necessary for the protection of the legitimate interests of the employer.
The burden of proof that the stipulation is valid is on the employer.