public function addMerchantPayment($application, \DateTime $effectiveDate, $amount, $token)
    {
        return $this->postDocument(
            '/v4/applications/' . $application . '/merchant-payments',
            [
                'amount' => $amount,
                'effective_date' => $effectiveDate->format('Y-m-d'),
            ],
            $token,
            'Add Merchant Payment'
        );
    }