Each policy of group life insurance shall contain a provision that: the policy is incontestable, except for nonpayment of premiums, after the policy has been in force for 2 years after its date of issue; and a statement made by an insured under the policy about insurability may not be used to contest the validity of the insurance as to which the statement was made unless: the insurance has been in force before the contest for less than 2 years during the insured’s lifetime; and the statement is in writing and signed by the insured.