CartMandateClass.fromSigned(signedMandate: CartMandate & { merchant_authorization?: string; },publicKey?: string,validateSignature?: boolean,keyConfig?: Partial<JWTKeyConfig>,expectedMerchantId?: string,expectedAudience?: string,): Promise<CartMandateClass>
Create from existing signed mandate
signedMandate: CartMandate & { merchant_authorization?: string; }
optional
keyConfig: Partial<JWTKeyConfig>
Promise<CartMandateClass>