Braintree/src/main/java/com/braintreepayments/api/ThreeDSecure.java
public static void performVerification(final BraintreeFragment fragment, final CardBuilder cardBuilder,
            final String amount) {
        TokenizationClient.tokenize(fragment, cardBuilder, new PaymentMethodNonceCallback() {
            @Override
            public void success(PaymentMethodNonce paymentMethodNonce) {
                performVerification(fragment, paymentMethodNonce.getNonce(), amount);
            }

            @Override
            public void failure(Exception exception) {
                fragment.postCallback(exception);
            }
        });
    }
public static void performVerification(final BraintreeFragment fragment, final CardBuilder cardBuilder,
            final String amount) {
        TokenizationClient.tokenize(fragment, cardBuilder, new PaymentMethodNonceCallback() {
            @Override
            public void success(PaymentMethodNonce paymentMethodNonce) {
                performVerification(fragment, paymentMethodNonce.getNonce(), amount);
            }

            @Override
            public void failure(Exception exception) {
                fragment.postCallback(exception);
            }
        });
    }
Verification is associated with a transaction amount and your merchant account. To specify a
different merchant account (or, in turn, currency), you will need to specify the merchant
account id when <a href="https://developers.braintreepayments.com/android/sdk/overview/generate-client-token">
generating a client token</a>

During lookup the original payment method nonce is consumed and a new one is returned,
which points to the original payment method, as well as the 3D Secure verification.
Transactions created with this nonce will be 3D Secure, and benefit from the appropriate
liability shift if authentication is successful or fail with a 3D Secure failure.

@param fragment the {@link BraintreeFragment} backing the http request. This fragment will
also be responsible for handling callbacks to it's listeners
@param cardBuilder The cardBuilder created from raw details. Will be tokenized before
the 3D Secure verification if performed.
@param amount The amount of the transaction in the current merchant account's currency