Model/Adminhtml/Source/GooglePayNetworks.php
public function toOptionArray() {
        return [
            [
                'value' => self::CARD_VISA,
                'label' => __('Visa')
            ],
            [
                'value' => self::CARD_MASTERCARD,
                'label' => __('Mastercard')
            ],
            [
                'value' => self::CARD_AMEX,
                'label' => __('American Express')
            ],
            [
                'value' => self::CARD_JCB,
                'label' => __('JCB')
            ],
            [
                'value' => self::CARD_DISCOVER,
                'label' => __('Discover')
            ],
        ];
    }
public function toOptionArray() {
        return [
            [
                'value' => self::CARD_VISA,
                'label' => __('Visa')
            ],
            [
                'value' => self::CARD_MASTERCARD,
                'label' => __('Mastercard')
            ],
            [
                'value' => self::CARD_AMEX,
                'label' => __('American Express')
            ],
            [
                'value' => self::CARD_JCB,
                'label' => __('JCB')
            ],
            [
                'value' => self::CARD_DISCOVER,
                'label' => __('Discover')
            ],
        ];
    }
public function toOptionArray ( ) { return [ [ 'value' => self :: CARD_VISA , 'label' => __ ( 'Visa' ) ] , [ 'value' => self :: CARD_MASTERCARD , 'label' => __ ( 'Mastercard' ) ] , [ 'value' => self :: CARD_AMEX , 'label' => __ ( 'American Express' ) ] , [ 'value' => self :: CARD_JCB , 'label' => __ ( 'JCB' ) ] , [ 'value' => self :: CARD_DISCOVER , 'label' => __ ( 'Discover' ) ] , ] ; }
Possible Google Pay Cards

@return array
Possible Google Pay Cards