Each group life insurance policy shall contain a provision that the policy and the applications of the employer and, if applicable, of the individual employees insured, are the entire contract between the parties, and that all statements made by the employer or by the individual employees shall, in the absence of fraud, be considered representations and not warranties. Any such statement shall not be used in defense to a claim under the policy, unless the statement is contained in a written application. For purposes of this section, an enrollment form is not an application described in this section.