Braintree/src/main/java/com/braintreepayments/api/internal/BraintreeHttpClient.java
@Override
    public void post(String path, String data, HttpResponseCallback callback) {
        try {
            if (mAuthorization instanceof ClientToken) {
                data = new JSONObject(data)
                        .put(AUTHORIZATION_FINGERPRINT_KEY,
                                ((ClientToken) mAuthorization).getAuthorizationFingerprint())
                        .toString();
            }

            super.post(path, data, callback);
        } catch (JSONException e) {
            postCallbackOnMainThread(callback, e);
        }
    }
@Override
    public void post(String path, String data, HttpResponseCallback callback) {
        try {
            if (mAuthorization instanceof ClientToken) {
                data = new JSONObject(data)
                        .put(AUTHORIZATION_FINGERPRINT_KEY,
                                ((ClientToken) mAuthorization).getAuthorizationFingerprint())
                        .toString();
            }

            super.post(path, data, callback);
        } catch (JSONException e) {
            postCallbackOnMainThread(callback, e);
        }
    }
Make a HTTP POST request to Braintree using the base url, path and authorization provided.
If the path is a full url, it will be used instead of the previously provided url.

@param path The path or url to request from the server via HTTP POST
@param data The body of the POST request
@param callback The {@link HttpResponseCallback} to receive the response or error.