is
fun isFreeTrialEligibleForCustomProduct(product: StoreProduct, entitlements: Set<Entitlement>, customerInfo: CustomerInfo, introOfferEligibility: IntroOfferEligibility = IntroOfferEligibility.AUTOMATIC): Boolean(source)
Entitlement-history-based trial eligibility for a custom (store == CUSTOM) product, mirroring the check used for web products in computeHasFreeTrial. Used at purchase time so a repeat purchaser who already consumed their trial does not generate a spurious freeTrialStart event — the external payment system charges them immediately.
Returns false when the product has no trial metadata, when eligibility can't be verified (e.g. no entitlements or customer info not yet loaded), or when the customer has ever held one of the product's entitlements.