How to combine PayPal SDK and Braintree SDK in android studio

Question

I want to implement a PayPal payment and a Braintree payment gateway.

I have use PayPalAndroidSDK-2.9.10.jar inside libs and

compile 'com.braintreepayments.api: braintree: 1.6.5' inside the app.gradle file.

The problem is that the PayPal and Braintree SDK have a duplicate class.

I need to combine both SDKs.

Note. PayPal and Braintree run at regular startup.