<virtualType name="BraintreeValidatorPool"
             type="Magento\Payment\Gateway\Validator\ValidatorPool">
    <arguments>
        <argument name="validators" xsi:type="array">
            <item name="country" xsi:type="string">
                BraintreeCountryValidator
            </item>
        </argument>
    </arguments>
</virtualType>

This is a virtual type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This virtualType configuration tells the Object Manager when a user wants a virtual BraintreeValidatorPool object that it should return a Magento\Payment\Gateway\Validator\ValidatorPool object.

This configuration tells the Object Manager that when a user wants a BraintreeValidatorPool object that the following arguments should be used in the foo object's constructor.

• $validators = [...items...];

<virtualType name="BraintreePayPalValidatorPool"
             type="Magento\Payment\Gateway\Validator\ValidatorPool">
    <arguments>
        <argument name="validators" xsi:type="array">
            <item name="country" xsi:type="string">
                BraintreePayPalCountryValidator
            </item>
        </argument>
    </arguments>
</virtualType>

This is a virtual type configuration.

This configuration is for the base area. Base area configurations will apply to all the sub-applications.

This virtualType configuration tells the Object Manager when a user wants a virtual BraintreePayPalValidatorPool object that it should return a Magento\Payment\Gateway\Validator\ValidatorPool object.

This configuration tells the Object Manager that when a user wants a BraintreePayPalValidatorPool object that the following arguments should be used in the foo object's constructor.

• $validators = [...items...];